Brian Galach’s 17th-minute goal has given Crawley Town a 1-0 half-time lead over the Blues at the Broadfield Stadium.
Town boss Paul Lambert named the expected very young side with Dylan Crowe and Levi Andoh making their Town debuts and Tommy Smith, Allan Viral, Zanda Siziba and Ross Crane their full Blues bows.
David Cornell, the most senior player in the side, skippered from between the sticks with former England U16, U17 and U18 international Crowe, 19, at right-back, Smith, 18, at left-back and Andoh and Corrie Ndaba, both 20, the centre-halves.
In midfield, Liam Gibbs, 17, was joined by Viral, 18, and 17-year-old Siziba, while Tyreece Simpson, 18, played down the centre of the attack with on-loan Borussia Mönchengladbach wideman Keanan Bennetts on the left and Crane, signed from Bury Town in the summer, on the right.
Among the six subs was forward Jack Manly, aged 16 years and 22 days. If he makes it onto the field the East Bergholt High School pupil will become Town’s second-youngster ever player.
As was the case in the previous game against Gillingham, the Blues face a £5,000 fine for contravening the competition’s selection rules.
Crawley changed all 11 of their players following their 6-5 FA Cup win at Torquay on Sunday and named only four substitutes but still more senior than the Blues’ team.
The home side struck the first shot of the game in the sixth minute, Ricardo German turning away from Ndaba, who had a good hold of his shirt, and taking the ball towards the edge of the box before scuffing his effort wide.
Crawley, who had had the better of the opening minutes, took the lead in the 17th minute through Galach. Sam Ashford whipped in a cross from the left and the striker headed into the ground and then the roof of the net from six yards.
The Town youngsters were trying to play their football but all too often a perhaps sometimes overambitious pass would go astray or would be cut out by a Crawley boot when getting into the final third.
The Red Devils might have done better in the 26th minute when Tarryn Allarakhia overhit a threaded pass straight to Cornell.
Chances continued to be a rare occurrence at both ends with Town maintaining their passing football but without being able to create an opportunity.
On 42 Crane brought the ball in from the right and fed Viral who had broken into the area but the French midfielder’s attempted turn sent the ball through to home keeper Stuart Nelson.
That was the nearest the Blues got to threatening a leveller before the half-time whistle was blown by referee Sam Purkiss.
Town had passed the ball around tidily at the back but had been unable to create anything of note against their more senior opponents.
Equally, Crawley had carved out few chances of their own with the goal the game’s one outstanding opportunity.
With Arsenal U21s having beaten Gillingham 4-2 on penalties in the evening’s other game following a 1-1 draw, the Blues need a point to qualify for the next round.
The Gunners youngsters have won the group with Crawley out regardless of what happens in the second half.
Crawley: Nelson, McNerney, Adebowale, Sesay, Ferguson, Allarakhia, Khaleel, Ashford, Galach, German. Subs: Tsaroulla, Kowalczyk, Burnett, Al-Hussaini.
Town: Cornell, Crowe, Andoh, Ndaba, Smith, Viral, Gibbs, Siziba, Bennetts, Simpson, Crane. Subs: Holy, Armin, Healy, Chirewa, Manly, Z Brown. Sam Purkiss (London).