(Bradford CIty win 3-2 on penalties)
By Chris Harris at the Coral Windows Stadium
Arsenal's hopes of lifting the Capital One Cup were dashed in a dramatic penalty shoot-out at Bradford City.
Bradford had led for much of normal time thanks to Garry Thompson's first-half volley which found the roof of the net after Gary Jones' free-kick was flicked on.
Vermaelen rescued his team with an equaliser three minutes left but, despite incessant pressure, Arsenal couldn't find an extra time winner.
They paid the price, despite two fine penalty saves from Wojciech Szczesny.
It was a numbing exit for Arsène Wenger's side, who had been hot favourites to secure their fifth semi-final appearance in 10 years.
One chance of silverware has gone. Now the Frenchman will have pick his players up ahead of Monday's Premier League trip to Reading.
Wenger made his intentions clear before this quarter-final tie when he said he would take a strong squad to the Coral Windows Stadium. He kept his word, and then some, making just three changes from the team that beat West Bromwich Albion on Saturday.
One of those - Olivier Giroud - was enforced, Alex Oxlade-Chamberlain and Mikel Arteta dropped to the bench and in came Lukas Podolski, Francis Coquelin and Aaron Ramsey. This was very much a 'Premier League' side and Wenger wanted his players to treat it like a top-flight game.
They had to.
Bradford, brimming with confidence after just one defeat in 11 games, went at their illustrious guests from the off. The classic 'little and large' strike partnership of Nahki Wells and James Hanson kept Per Mertesacker and Vermaelen busy while Nathan Doyle snapped into tackles in front of his back four.
Arsenal would have expected an early storm and at times they struggled to weather it. Szczesny got down well to save from Wells in the sixth minute and the Pole dealt bravely with Hanson as he charged through on goal.
Slowly but surely, the visitors seized a semblance of control and threatened through headers from Vermaelen and Podolski. But they were hit by a sucker punch after 16 minutes.
Gary Jones curled in a free-kick from just inside the right touchline, a flick-on landed at Thompson's feet and he volleyed into the roof of the net with Szczesny unable to get more than a fingertip on the ball. The next set-piece was almost as costly but Gibbs was on hand to clear off the line after another fine Jones delivery.
Arsenal's task suddenly looked rather more onerous but this was no time to panic.
Initially rattled, the visitors - driven on by Jack Wilshere - started to push Bradford back. Facing two banks of four, Arsenal struggled for penetration at first but that all changed when Coquelin took matters into his own hands.
The French midfielder ghosted past two opponents on the edge of the box and fired in a low shot that bounced off the post. Sagna clipped the rebound to Cazorla but the Spaniard could not keep his first-time effort down.
They were getting closer though, and three minutes before half-time should have levelled. A flowing Arsenal move culminated in Wilshere picking out Gibbs' run and his low cross was somehow diverted wide by Gervinho, just two yards from goal.
Bradford remained a threat after the break and forced a succession of corners which Arsenal defended well. But as the second half wore on, predictably, the visitors saw more and more of the ball.
How they used it would be decisive and, for all their efforts, clear-cut chances were at a premium.
A quick break 10 minutes into the half saw Cazorla find Ramsey inside the box. The Welshman found space for a shot but sliced his shot wide. Moments later Gervinho's pace took him beyond the Bradford defence but his touch let him down and the opportunity went begging.
This was a good spell for Arsenal. Coquelin, full of energy before he was replaced by Chamakh, burst into the area but could not pick the right pass. Then Gervinho side-footed wide from 12 yards out.
Wenger introduced Tomas Rosicky and Oxlade-Chamberlain and they had an instant impact, linking up on the right for the latter to force a good save from Matt Duke.
The other substitute, Chamakh, headed over with 20 minutes left and Wilshere was next to go close with a rasping drive from the edge of the box. Once again Duke did well but no Arsenal player could reach the rebound.
Oxlade-Chamberlain fired wide with six minutes left and the game seemed to be up. Then Cazorla's cross was nodded in by Vermaelen at the far post to finally give 4,500 cold travelling supporters something to cheer.
Duke made two fine saves from Cazorla to take the tie into extra time and by now it was one-way traffic.
Sagna had a header cleared off the line, Duke brilliantly denied Gibbs and Oxlade-Chamberlain also went close. Cazorla went closer still with a wonderful effort from 25 yards that crashed off the bar.
Bradford held on valiantly and would have fancied their chances in a penalty shoot-out. The League Two side have never lost one and beat Wigan in that manner in the last round.
Duke saved from Cazorla and Chamakh hit the post to put Bradford in control. Szczesny threw Arsenal a lifeline, saving from Darby and Wilshere, Alan Connell and Oxlade-Chamberlain all scored before Szczesny denied Ritchie Jones the chance to win it.
The tide seemed to be turning yet again but Arsenal's luck quickly ran out.
- Vermaelen (C) Goal! Yellow Card
- Ramsey 69
- Coquelin 60
- Gervinho Yellow Card
- Podolski 69
- Rosicky 69
- Chamakh 60
- Oxlade-Chamberlain 69
- Doyle Yellow Card
- Thompson 72 Goal!
- Atkinson 92
- Jones (C)
- Wells 74 Yellow Card
- Hanson Yellow Card
- Jones 72
- Connell 74
- Turgott 92