"I love to see them on the front foot – I can't keep them back.

"I've got Paddy McNair doing overlaps in the 93rd minute and I thought Britt (Assombalonga) looked good and sharp.

"What can you say about 'Wingy' (Lewis Wing)? I thought (George) Saville was outstanding and little Sam (Morsy) ended up at centre half at the end.

"The two centre-halves were immaculate and everything that happened in midfield was around Saville. So I'm really pleased for them all because they're a good group.

"Paddy has brought the best out of Dael (Fry). I put my arm around them both coming off, saying 'you two have been brilliant – I can't remember too many better partnerships I've had'."

It was Middlesbrough's biggest league win since they beat Ipswich at home by the same scoreline on March 14, 2015 and heaviest away league victory since beating Millwall 5-1 on December 6, 2014.

"It's a long time since we scored four away from home but there were some good goals," added Warnock.

Blues have now lost their last three and gone six without a win at home after their biggest league defeat since losing 5-0 at Brentford on February 20, 2018.

It was their heaviest home league loss since February 18, 2017 when they were beaten by Queens Park Rangers by the same scoreline.

Birmingham head coach Aitor Karanka said: "It is difficult to take but it's not the first time we have lost at home after leading, conceding goals with individual mistakes.

"If we had not played well since the beginning of the season I would be concerned. But 10 days ago we showed we can compete face-to-face with the teams fighting for the play-off positions.

"My concern now is why? We can beat teams away and we can't do the same things at home.

"I'm really disappointed. We started the game really well – it seemed like the players understood the plan.

"But once again when we scored the first one, we conceded two in five minutes."

The game was already heading Boro's way when Birmingham goalkeeper Neil Etheridge made mistakes for the visitors' final two goals.

"I always said he is one of the best keepers in the league and he belongs in the Premier League," added Karanka. "I don't want to change my mind because he made two mistakes. He was, he is and will be really important for us."

Blues led when Maxime Colin crashed a rising left-foot drive into the top corner from 15 yards in the 15th minute.

Assombalonga levelled in the 27th minute with a cool finish across Etheridge and Saville put Middlesbrough ahead four minutes later when he side-footed home a left-wing cross from Marvin Johnson.

Etheridge allowed Wing's inswinging corner to drop through his hands in the 56th minute for an own goal and could not stop Wing's low 25-yard drive eight minutes from time.