If Paul Lambert thought he had problems, he knows he has now. Never mind the late Aston Villa goal that made the scoreline more respectable. Ignore for the moment the fact that Villa have a home leg in which to make amends. Consider instead that amateurs would have blushed at the Villa defending that led to Bradford's second goal, that even after getting back into the game the Premier League side were undone by allowing Carl McHugh a free header at a corner two minutes from time, and that James Hanson rattled Shay Given's crossbar with a header inbetween.

Bradford were by no means flattered by their victory, whatever it turns out to mean. What a dramatic night in West Yorkshire already means for Villa is their confidence, already at rock bottom, is going to need some sort of fracking process if it is to resurface in time to be of any assistance in league fixtures and the ongoing fight against relegation. Lambert has done a lot in football, but turning this situation around is a challenge of superhuman proportions.

Yet for almost 20 minutes it appeared Aston Villa were about to prove that Arsenal were a bunch of southern softies who slipped up here because conditions were turning icy underfoot. On a much milder evening than the weather forecasters had predicted the Premier League side began as if determined to make full use of a soft and forgiving surface, keeping the ball on the floor at every opportunity and using their superior passing and movement to create a host of early chances. Charles N'Zogbia had two decent efforts saved in the first eight minutes, Christian Benteke also hit the goalkeeper when he should have scored after timing a run through the Bradford cover, and every time the home side conceded a corner it seemed Benteke would get a free header.

In short, Villa could have been a goal or two to the good by the time Bradford announced they would not just be lying down and admiring their opponents' attacking ideas. All they seemed to have to do was keep their composure and wait for the goals to arrive, for with the freedom Benteke was finding, it appeared unlikely he would spend the whole evening missing the target. Then Bradford got a lucky break from a free-kick, not just with the rebound that fell kindly but with a linesman alert enough to realise that Nahki Wells was still onside, and the Bermudan finished with a coolness that made Villa's earlier efforts look laboured.

Suddenly the Bantams grew in stature while Villa visibly withered before Lambert's eyes. Bradford have hardly been excelling themselves in the league of late – in six matches since knocking Arsenal out of this competition they have managed just one win – but at least they are not in any immediate danger of relegation.

Villa's precarious position just ahead of the Premier League relegation places seemed to flash before them as soon as they went behind, raising doubts, stripping confidence and eating away at their ability to stay in control. Although Matt Duke was required to make a good save from Gabriel Agbonlahor right at the end of the first half, between that and the opening goal the action was all down the other end as Villa retreated into their shell.

Zavon Hines was making huge inroads down the right, bringing a save from Given before providing a cross from which Hanson might have done better, though arguably the best chance of a second goal before the interval was when Hanson saw a header hacked off the line following a corner.

It was complete role reversal within the space of half an hour, and if Lambert had done well to get his side to put their league worries behind them and play with authority in the opening stages, his half-time task was to raise his players' chins from the floor and restore their obviously fragile self belief. After some of the heavy defeats Lambert has experienced in recent weeks, he hardly needed being on the wrong side of a David v Goliath encounter adding to the list, even if the immediate damage is recovered at Villa Park in a fortnight.

The visitors opened the second half with some conviction, Duke saving from first Benteke then Agbonlahor to preserve his side's lead, though within minutes the first half pattern had been re-established, with Bradford turning defenders with ease and invariably finding yards of space behind them.

You could tell Lambert was worried, because he sent on Darren Bent with more than half an hour to play. Here was an ideal opportunity for the discarded striker to prove a point, even against lower league opposition. Bent volleyed too high with his first chance, admittedly a difficult one, then made a complete mess of a point blank header with the goal at his mercy after Duke had flipped N'Zogbia's drive into the air.

By the end both teams were looking bedraggled, with Bradford grimly holding on to their lead and Villa focusing mainly on not allowing them to extend it. A single goal defeat would not have been too bad, but Villa could not even manage that, and the manner in which they conceded the second goal will have made Lambert furious.

When a corner was half-cleared, Villa made a less than half-hearted attempt to tidy up, allowing Wells to nip in front of a defender to ensure Bradford could retain possession and have another go. Rory McArdle's unanswerable header, followed by McHugh's unstoppable one, means Bradford will be having yet another go at Villa Park. Unlike Lambert's team, they have nothing to lose and all the momentum in the world behind them.