A young Arsenal side, even by the standards of Carling Cup sides selected by manager Arsene Wenger down the years, overcame the Championship leaders thanks to two goals in the space of seven second-half minutes.

They ran out fairly comfortable winners, but their task was made much easier by the foolish dismissal of the visitors’ Jerome Thomas late in the first-half.

West Brom were starting to take control of proceedings when Thomas pushed Arsenal’s Jack Wilshere to the ground, the former Arsenal youngster seeing red for his petulant reaction after the two had contested possession.

And the introduction of Mexican Carlos Vela stretched the under-manned Baggies to breaking point in the final quarter.

Arsenal had famously beaten Sheffield United 6-0 at this stage of last year’s competition. And with the relatively ancient Philippe Senderos coming close with a header during some early Arsenal pressure, another convincing win looked on.

But the Gunners Wojciech Szczesny was the busier keeper for much of the first-half, producing his best save to deny Robert Koren, with Simon Cox also coming close.

Sanchez Watt, scorer of two goals in last season’s FA Youth Cup final and semi-final, struck a post on 17 minutes with Arsenal’s best chance of the half.

The second period became more open and Watt was on-hand to give the North Londoners the lead on 68 minutes, following up after Baggies keeper Dean Kiely had parried a Vela shot.

Vela added the second goal himself, taking advantage of some poor defending to nip in and score after Mark Randall’s deft chip from 20 yards had come back off the crossbar.

West Bromwich Albion boss Roberto di Matteo not surprisingly pinpointed the sending-off as the game’s crucial moment: “That was the turning point. Before then we were starting to get on top.”

Wenger, meanwhile, praised Vela’s contribution as “something a bit special.”