Good evening ladies and gentleman, and welcome Arsenal fans to unfamiliar territory. After 19 years straight seasons in the Champions League, the Gunners find themselves playing on Thursday nights.

Arsenal were served an unwanted reminder of what they will be missing by fierce rivals Tottenham last night. They have laid the gauntlet down in North London with their 3-1 win over Borussia Dortmund.

The Gunners too welcome German opposition this evening. FC Koln - bottom of the Bundesliga and without a point this season - are the visitors to the Emirates. Team news on its way shortly...

ARSENAL: Ospina; Holding, Mertesacker, Monreal; Bellerin, Iwobi, Elneny, Maitland-Niles; Welbeck, Giroud, Sanchez

Subs: Macey, Mustafi, Kolasinac, Reine-Adelaide, Nelson, Wilshere, Akpom

FC KOLN: Horn; Rausch, Heintz, Mere, Klunter; Lehmann, Bittencourt, Hector, Hoger, Zoller; Cordoba

Subs: Kessler, Sorensen, Risse, Jojic, Osako, Guirassy, J. Horn

Nine changes for Arsenal from Saturday's 3-0 win over Bournemouth. The headline news is the inclusion of Alexis Sanchez for his first game of the season. Ainsley Maitland-Niles also starts.

BREAKING NEWS: The kickoff for this match has been delayed by an hour - until 9.05pm

The kick-off of #AFCvCOL has been delayed by an hour in the interests of crowd safety — Arsenal FC (@Arsenal) September 14, 2017

Big news coming out of the Emirates. Tonight's kickoff has been delayed for an hour. Neither club are yet to offer an explanation, but Sky Sports reports that it is because of sporadic crowd trouble.

This video of Koln supporters invading London has been doing the rounds on Twitter ahead of kickoff. Apparently 20,000 of them have travelled from Germany. The behaviour here looks passionate, but not aggressive. So hopefully things haven't turned nasty between the two sets of fans.

20,000 FC Koln fans have travelled to London for their game at the Emirates & they're taking over...😅 (@emandagoonn) pic.twitter.com/lzoD0VsBSq — The Away Fans Videos (@TheAwayFansVids) September 14, 2017

More from Sky Sports now on the crowd trouble. They claim that some groups of Koln fans have managed to storm a barrier outside the Emirates, and this provocative action has caused a few incidents which have threatened the safety of the fans. Worrying stuff.

This will be unsettling to the players as well as the supporters. They would have been just about to emerge for the warm-up when the delay was announced. But of course, supporter safety must take priority.

While this situation is resolved - hopefully safely for everybody - I'm off to catch the end of the Everton game. You can follow it here. I'll be back in 45 minutes with an update, and hopefully some football.

Here's an update on what we've learned and where we stand with this match:

- Talks taking place between clubs and UEFA to decide whether the game goes ahead

- Concern over the number of away fans who've arrived without tickets. Estimated 20,000 Koln fans have travelled, despite a 2,900 ticket allocation

- Koln supporters may have obtained tickets for Arsenal allocated areas

- Police have dealt with 'minor scuffles' inside the Emirates Stadium

Not the sturdiest fan footage, but this video appears to show Koln fans forcing their way through barricades in order to try to access the home end.

SCENES: @FCKoeln fans invade The Emirates as they force entry into the home end. 😳💥
(🎥 @PED7)
pic.twitter.com/lF0g0SICz9

— SPORF (@Sporf) September 14, 2017

It should be stressed that, apart from a couple of minor incidents inside the stadium, there is no reports of serious fan violence. The problem is the sheer number of Koln supporters trying to access the stadium and whether that jeopardises the safety of the fans of both teams.

Pretty much everyone you see in this pic are Cologne fans - All those in the Arsenal end. They are everywhere. pic.twitter.com/5ca4X2S8Nt

— Charles Watts (@charles_watts) September 14, 2017

At this rate I'd be surprised if this game goes ahead. There appears to be thousands of Koln supporters who have managed to invade the stadium, outside of the away end. I can't see how fan safety can be guaranteed.

Police are attempting to control the crowd and separate the fans outside the stadium.

Bridge to Drayton Park blocked. Guards around Emirates say discussions between Uefa & clubs whether game goes ahead pic.twitter.com/ANNd2wJ1If

— Sam Wallace (@SamWallaceTel) September 14, 2017

There has been no further announcement about the kickoff time. So, as it stands, the match will start at 9.05pm. We will keep you posted if there are any changes to this.

BREAKING Arsenal say that the situation is under control and that the game will kick-off at 9.05pm — Sam Wallace (@SamWallaceTel) September 14, 2017

If this is what 'under control' looks like, I'd hate to think of the scenes if things get out of control during the match. Koln fans are basically occupying Arsenal territory. Appears there is a lot of work to do before 9.05pm to make this a safe environment.

Fc koln fans fighting with arsenal fans and stewards #arsenal #Emirates pic.twitter.com/ilRUJ1KWKG — Ashley Smith (@Ash9423) September 14, 2017

Let's try and focus on the football shall we, and trust the police to do their jobs. Nine changes for Arsenal. Nacho Monreal and Hector Bellerin are the only players retained from the 3-0 win over Bournemouth. Goalscorers Alexandre Lacazette and Danny Welbeck drop out. Alexis Sanchez starts.

No doubt that Arsene Wenger is prioritising Sunday's London derby with Chelsea, but this Arsenal team still looks strong enough to begin their Europa campaign with a win; Sanchez, Giroud and Walcott up top.

The Gunners' bench makes interesting reading. No Lacazette, Welbeck or Ozil in reserve - they are all given the night off. Instead, youngsters Jeff Reine-Adelaide and Chuba Akpom. And there is a spot for Jack Wilshere too.

Just an update on the crowd situation. Reports are claiming that Koln fans signed up for Arsenal memberships and bought shirts to wear on the night in order to sneak into the Emirates. That's dedication!

What this delayed kickoff means now is a finish time of gone 11pm. That is not ideal preparation for Arsenal with such a big Premier League game at the weekend. Not ideal for the commuters either!

This lack of crowd segregation should create a unique atmosphere in the Emirates tonight. The players will be used to the generally restless surroundings of the last 18 months. This will be quite different.

This is Koln's first European match in 25 years; hence the excitement of their supporters. But how have Arsenal allowed so many memberships to be sold to German residents at short notice?

Less than 15 minutes until kickoff here. The players have been warming up. Sanchez back in the lineup tonight. He was the subject of boos from some sections of the home crowd on Saturday.

Others to watch out for tonight are Olivier Giroud - he has a point to prove having lost his place in the Premier League XI - and youngster Maitland-Niles on the wing. It is his fifth start in all competitions - all previous have come in the FA or League Cup.

HEAD-TO-HEAD These two teams have only met once previously - in a two-legged 1970/71 Fairs Cup tie which Arsenal won on penalties after a 2-2 draw on aggregate. Can Arsenal make it a North London double over German oppo?

PREDICTION: It is a much-changed Arsenal side but they can still field nine full internationals and have a couple of x-factors in attack. Koln are enduring their worst Bundesliga start in 40 years and should be easy pickings. Their supporters will try to even up the playing field though.

One to watch for FC Koln is £17m striker Cordoba. Their replacement for 25-goal Anthony Modeste - who went to China in the summer - has not really started firing yet. Jonas Hector is Germany's number one left-back and a fine player. Theo Walcott will do well to get the better of him.

KICKOFF Arsenal get us underway, and their every touch is being booed by this German invasion of a crowd.

Wenger is persisting with the fashionable three-at-the-back formation. It is fair to say Arsenal are not comfortable with the system yet. This could be a good game for them to bed themselves in.

A difficult start for Holding, who has given a couple of free kicks away in the Arsenal third for fouls on Bittencourt. Both of the set pieces were cleared without any trouble.

Koln may have been out of Europe for 25 years but they do have some continental pedigree. They reached five European semi-finals in the 1960s and 1970s, and were UEFA League runners-up in 1986.

The 20,000 travelling Koln fans - those that managed to sneak in - are on their feet. An amazing goal from Jhon Cordoba, but a howler from David Ospina. The Colombian's scuffed clearance eventually falls to Koln's £17m signing, who turns and quickly shoots into the vacant goal from 40 yards. Stunning! Brilliant awareness from the striker and the execution is even better.

Giroud has a looping header tipped over the bar by Timo Horn. Offside flag was raised anyway. The Frenchman is looking for his 100th Arsenal goal tonight.

Monreal gets decent contact on a corner whipped into the near post, but Horn holds his header.

Zoller makes an unchecked run off the right flank. Arsenal eventually clear despite Mertesacker and Monreal stumbling over the ball and nearly giving the winger a sight of goal.

Good move from Arsenal. They go wide to Bellerin who takes it first time and lofts the ball into the box. Giroud easily wins his header but can't generate enough power to test Horn.

We've seen very little of Sanchez so far. A visit of Koln in the Europa League probably wouldn't have been in his plans for this season. He needs to get his head on now though. His team need him.

CHANCE! Big opportunity for Arsenal to equalise. Iwobi delicately lifts a ball over the last man for Walcott, who screws his shot five yards under the pressure of a defender.

Midway through the first half and this has the makings of a bad night for Arsenal. As if being invaded by German supporters wasn't enough, they are trailing 1-0 to the Bundesliga's bottom club.

Koln are playing with growing confidence. They've pinched a goal thanks to Ospina's gaffe and have largely kept Arsenal at bay. They attack down the right and win a corner. An ambitious Paul Scholes-esque tee up to the edge of the box goes horribly wrong, but the hosts can't counter.

Fantastic early delivery from the left-back Rausch splits the Arsenal defence and goalkeeper. Zoller is offside and Ospina manages to block at the near post. Nervy moments before the flag was raised.

Elneny slices a half volley harmlessly wide from 20 yards. Not the man Arsenal want the ball falling to. In another mood it would be Sanchez, but he seems disinterested and has misplaced several passes.

SUBSTITUTION: Big blow for Koln as Hector is forced off. He tried to run off a knock to the ankle sustained during a collision with Ospina a few minutes ago, but to no avail. Milos Jojic is on.

Sanchez comes alive and slips Maitland-Niles in by the left byline. His cross is turned away at the near post.

CHANCE! Iwobi runs at the Koln defence and tees up Sanchez for a cross which is headed wide by Giroud from 12 yards. That's a really good chance for somebody as skilful in the air as he is. Better from Arsenal. Can they snatch an equaliser before half time?

Bittencourt breaks down the left for the visitors. Cordoba is screaming for the ball in the middle, but the cross is too long in coming and Elneny recovers to block the ball behind for a corner.

Arsenal have the Germans pinned back in the final stages of this half. Giroud has a shot blocked, and Dominique Heintz makes a very good clearing header from a follow-up Monreal cross.

Maitland-Niles runs the ball out in the left corner and that's about that for this half.

This game had a chaotic build up and things haven't got much better for Arsenal. Ospina's scuffed clearance gifted Koln an early lead and they haven't created much in terms of equalising chances despite having 71% possession.

Ospina will rightly be criticised for that goal, but Jhon Cordoba deserves huge credit for the composure and vision that he displayed to capitalise on that mistake. A goal he will remember forever.

RESULT: Elsewhere in Arsenal's group, Red Star Belgrade and BATE Borisov have drawn 1-1 - remember that was an 8.05pm kickoff. At this rate, the Gunners will be bottom of Group H this evening.

BENCH WATCH Wenger hasn't given himself many established options to turn to on the bench. Jack Wilshere would improve this team. At the moment, Elneny is being asked to drive forward with the ball and Wilshere, although likely rusty - would be much more effective in that role.

Another tactical shift that Wenger could make would be to move Sanchez inside to get him more involved in the game. He's not had enough of the ball on the left would be more of a threat closer to Giroud.

KICKOFF: We are back underway at the Emirates. Pleased to report that there has been no sign of any crowd trouble since the game started. Let us hope that continues until full time.

SUBSTITUTION: News of an Arsenal change to bring you at the break. Summer signing Sead Kolasinac is on for Rob Holding, so that looks like Wenger has switched to a back four.

You can understand why Sanchez gets frustrated sometimes. He shows unbelievable footwork to escape from 3-4 defenders and then dinks a ball over the top for Walcott, who is flagged offside. He is looking right along the line there. No excuses. Although, actually, he may have been hard done by!

That probably wasn't the impact Wenger was expecting that substitution to have! Walcott this time does time his run to stay onside. His cross is blocked and eventually ricochets to Kolasinac, who smashes a ferocious left-footed volley past Horn and into the bottom corner. Great strike.

Kolasinac has made a real difference. He gets to the byline and his pacey cross is cleared in a panic by Lukas Kluntler. Sanchez's follow-up ball picks out Iwobi, who side foots a half-volley over the bar.

Sanchez is starting to make things happen. He releases Bellerin down the right. The cross is into a good area but Walcott cannot control a difficult chance at the near post. Heintz was marking him tightly.

A chance now for Kolasinac to show off his defensive strength as he prevents a breakaway down the Arsenal left. He needs to start against Chelsea on Sunday. He's designed for English football.

Arsenal are taking control of this game and, for the first time, the German fans are quiet.

SHOT! What was I saying? Koln break 3-on-3 but Holger decides to take the shot on from range but Ospina holds at the second attempt.

CHANCE!: The Emirates was about a foot away from having a new hero there. Maitland-Niles exchanges a couple of one-twos on the edge of the box and tries to round Horn, who stretches out his hands to prevent the youngster from getting away from him.

Pep Guardiola, look away now. Alexis Sanchez is back with a flourish, cutting inside from the left, dribbling across two players and bending an unstoppable shot into the top corner. Arsenal lead 2-1 and the Emirates rises to their hero. How quickly football fans can forgive and forget.

SUBSTITUTIONS: Jack Wilshere wears Arsenal red for the first time in 12 months. He's on for Alex Iwobi, who may be in Wenger's plans for Sunday. A Koln change too - Marcel Risse on for Zoller.

SAVE! Cordoba has the chance to run Monreal one-on-one and gets to the edge of the box before firing a low shot which Ospina gets behind at his near post. Arsenal must stay switched on.

Lovely move from the Gunners. Giroud's first-time layoff forces Walcott a bit wide when a better touch would have set the England international up on goal. Moments later, Horn saves a Sanchez free kick.

Arsenal are on the hunt here. They want a third to kill this game off.

CHANCE! Wilshere threads through Sanchez, who spoons a shot well wide.

Hoger tries his luck from range but Ospina is solid in behind that one.

That's a nerve-settler for Arsenal from Hector Bellerin. The hosts switch the play quickly - in part thanks to a delightful dummy from Wilshere. Walcott's shot is saved by Horn, but an opportunistic Bellerin is on hand to poke the ball home from six yards for his first European goal.

Koln and their travelling army of supporters have played their part tonight, but that should be that. An important result for Arsenal - heading to Chelsea on the back of a defeat would have been disastrous.

SUBSTITUTION: A late run out for 17-year-old prodigy Reiss Nelson. Walcott is off, icing his leg.

Could have had a goal at each end. Cordoba's shot is blocked at the near post moments after Sanchez's cheeky lob from an impossible angle lands just wide. The build-up play was Arsenal at their best.

Arsenal survive a scare in their opening Group H game. They were shocked by Cordoba's stunning opener, and their recovery was a while coming but second-half goals from Kolasinac, Sanchez and Bellerin eventually saw off the Germans.

Wenger should be pleased with that second half display. His side reacted well to the change of formation and by the final 20 minutes were close to their fluent best. Sanchez scoring is a huge bonus. Hopefully that will help him reintegrate into the squad ahead of their Premier League return.

Read our match report on Arsenal's 3-1 victory here. They top Group H tonight.

Anyway, it is way past my bedtime. I'm sure we will be reading more about that crowd trouble tomorrow. On the pitch, three important points for Arsenal, though. They now head to Chelsea on Sunday. Join Sports Mole for live coverage of that one from 12.30pm. Until then, goodbye!