Last season's League One and League Two champions will face off in the opening round of the EFL Cup on Tuesday.
Plymouth Argyle held off stiff competition to win League One with 101 points, while Leyton Orient lifted the League Two title with 91 points.
Match preview
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Indeed, Plymouth competed in their first Championship match since 2010 when facing Huddersfield Town on Saturday, with Steven Schumacher's side running out resounding 3-1 winners.
The Pilgrims got themselves off to the perfect start when Morgan Whittaker opened the scoring after just six minutes, sending Home Park's capacity crowd into rapture, before second half strikes from Bali Mumba and Ryan Hardie ensured their momentum from last season continued into this one.
Schumacher will have been delighted to have secured Whittaker and Mumba - who were both crucial loanee captures during the side's title-winning campaign - on permanent deals from Swansea City and Norwich City respectively.
Having been knocked out of this competition at this stage by Peterborough United last season, Schumacher and his players will sense an opportunity to advance at least one round further having been drawn against a lower-ranked team on Tuesday.
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Leyton Orient were also eliminated from the opening round of the EFL Cup last season, losing 2-0 to Forest Green Rovers, but Richie Wellens is unlikely to be prioritising this competition.
The O's will have their sights set on securing survival in League One following their promotion from the Football League's bottom tier last time out, with this being their first season in the third tier since being relegated from it in 2015.
They have only advanced beyond the first round of the EFL Cup on one occasion in those ensuing eight seasons, suggesting they are unlikely to have much chance of causing an upset away to their Championship opponents in midweek.
Their first match back in League One ended in a 1-0 defeat away to Charlton Athletic on Saturday, with George Dobson's strike for the hosts on the stroke of half time ultimately proving the difference between the two sides during a closely-fought battle, but Wellens will have taken plenty of confidence from his side's opening day performance.
Team News
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With his side set to travel to Watford on Saturday, Schumacher may look to make wholesale changes to allow his fringe players an opportunity to impress him and his backroom staff when Leyton Orient arrive in Devon.
The former Everton academy midfielder named an extremely youthful bench against Huddersfield at the weekend, but Matt Butcher should help provide experience in the engine room after being left out of the starting XI for the victory.
Likewise, Wellens may look to rest key players after losing to Charlton on Saturday, with former Ipswich Town players Joe Pigott and Idris El Mizouni both potentially dropping to the bench after making their debuts for the club.
George Moncur will almost certainly start after surprisingly being left out of the team during his side's defeat at The Valley, while Ed Turns may come into the visitors' defence.
Plymouth Argyle possible starting lineup:
Burton; Kesler-Hayden, Gillesphey, Pleguezuelo, Galloway; Butcher, Warrington; Wright, Azaz, Miller; Waine
Leyton Orient possible starting lineup:
Howes; Turns, Beckles, Thompson; James, Brown, Moncur, Sweeney; Graham, Agyei, Drinan
We say: Plymouth Argyle 2-1 Leyton Orient
With both managers likely to make wholesale changes for this match, it could be an open match at Home Park, with plenty of mistakes and a lack of match fitness on display.
However, the hosts should be able to call upon greater strength in depth having signed some quality first-team players during the summer transfer window, and we expect them to narrowly progress to the second round.
For data analysis of the most likely results, scorelines and more for this match please click here.
