By Rob Bishop
Gabby Agbonlahor was Villa's super sub at Upton Park, heading the stoppage time winner which sank relegation-haunted West Ham and lifted Gerard Houllier's men into the top half of the table.
Agbonlahor had replaced Emile Heskey in the 77th minute and his dramatic late goal was just reward for an excellent Villa performance which also featured record signing Darren Bent's sixth goal in 11 games.
Robbie Keane, so often a thorn in Villa's side during his Tottenham days, fired the Hammers ahead in the second minute and Villa were on the back foot for long periods of the opening half.
But Bent's 37th-minute equaliser changed the complexion of the game, with Villa well on top throughout the second period.
Although Stiliyan Petrov tried his luck after just 16 seconds with a shot which was well wide, the Londoners were more dominant in the early stages, going ahead before two minutes had elapsed.
Mark Noble's left-wing corner was only half cleared, and when former Villan Thomas Hitzlsperger nodded the ball back into the goalmouth, Keane turned sharply to fire left-footed past Brad Friedel from six yards.
Villa defenders appealed strongly for offside but referee Mark Halsey was adamant it was a perfectly good goal - a view supported by video evidence which suggested Keane was played onside by Ashley Young.
After Luke Young had slid in to clear a Carlton Cole shot for a corner, Young produced the visitors' first attempt in the seventh minute, the winger's shot being deflected into the side netting following a superb crossfield pass from Bent.
Friedel was forced to race out and kick clear when Cole moved menacingly on to a long through ball from Victor Obinna, while the home side appealed for a penalty when former Villa loanee Cole went down under Richard Dunne's challenge, although referee Halsey ruled it to be fair.
West Ham were still on top at this stage and although Ashley Young tested home keeper Robert Green with a skidding low drive, Villa were grateful for Friedel when he tipped away Cole's low shot for a corner.
Even so, Villa thought they had equalised on 23 minutes, Bent heading home Downing's cross from the right, only be penalised for a push on full-back Lars Jacobsen.
But that gave Houllier's side fresh impetus and after another Bent header had deflected off Daniel Gabbidon for a corner, there was an equaliser for travelling fans to celebrate.
Heskey dispossessed Noble as the midfielder attempted to play his way out of trouble in the penalty area before Ashley Young touched a short pass to Luke Young for the left-back to deliver an inviting cross.
Bent, perfectly positioned right in front of goal, was only too happy to accept the invitation with a clever glancing header which left Green helpless as it nestled in the bottom corner.
It was just the boost Villa needed and they must be wondering how they failed to score in a spell of total dominance immediately after the interval.
Bent capitalised on Matthew Upson's misplaced header to unleash a low angled drive which Green managed to scramble away for a corner, James Collins meeting Young's flag kick with a header which was cleared from the goalmouth.
Then Petrov touched a short free-kick to Young, whose shot was curling towards the far post until Green stretched to tip it away for a corner.
And when Bent worked his way into a good position for a low shot from the edge of the penalty area, the Hammers were more than relieved to see it take a deflection for yet another corner.
Having already made two substitutions, the home side were forced into a third in the 63rd minute, Gary O'Neil being stretchered off following a hard but fair challenge by Nigel Reo-Coker.
Villa were still calling the shots, though, and Young wasn't far off target with a 20-yarder following an exchange of passes with Bent, although the record signing should have done better with a glorious chance in the 73rd minute.
Kyle Walker created the opening with a fine run down the right before cutting the ball back. Bent's initial control was good but he then mis-kicked, stubbing his shot harmlessly into Green's arms.
As Villa maintained their momentum, Young's sidefoot effort drifted just beyond the far post, while Reo-Coker tested Green with a well-struck 20-yarder.
But just as it looked as if they would have to settle for a point, the visitors got the reward they deserved in stoppage time, Young crossing from the right for Agbonlahor to head in from close range.