Javier Hernandez produced a remarkable substitute performance as Manchester United came from two down to beat Aston Villa 3-2 in the Premier League.
The Mexican scored twice and had a shot turned in for an own goal as he transformed United's fortunes at Villa Park.
But Hernandez pulled one back with a deft finish through Brad Guzan's legs, before Ron Vlaar inadvertently deflected a volley past Guzan for the equaliser.
Then in the 87th minute, Hernandez completed the rescue act, meeting Robin van Persie's free-kick with a cushioned header into the right corner.
It was Hernandez's seventh goal in five games - not a bad return for a player who could hardly get a game at the start of the season, and who must settle for an impact sub role in United's biggest games.
The win ensured Alex Ferguson's men end the weekend top of the table, a scenario that seemed remote after Weimann's second goal on 50 minutes.
Barcelona's defeat at Celtic in midweek demonstrated the futility of possession without and product, and we saw another example - albeit less extreme - at Villa Park.
As United's pass tally soared with countless balls inside their own territory, it was Villa who actually made their 27 per cent first half possession count.
Ashley Young made a telling last-ditch tackle in defence as the ball dropped to Christian Benteke following a corner, while poor final passes from Weimann and Stephen Ireland put paid to promising counter-attack opportunities.
Gabriel Agbonlahor and Benteke flashed crosses in front of goal, while at the other end United looked bereft of ideas once they got into the final third.
Paul Scholes had a lucky escape when Ireland caught him in possession 25 yards from his own goal and set up Benteke - winning a questionable free-kick for the Villa man's challenge.
As the first half stumbled towards an apparently goalless conclusion, United conceded the first goal for the seventh time in 11 Premier League games.
Chris Smalling, playing for the first time this season, was swatted aside by Benteke, who crossed low for Weimann at the edge of the box - the Austrian met the ball with an emphatic sidefoot shot that flashed past David De Gea into the roof of the net.
The United defender claimed Benteke fouled him in the build-up, but this was shoulder-to-shoulder contact - the only reason Smalling ended up on the floor was because Benteke proved stronger.
And though Weimann struck the ball powerfully, De Gea might have got a hand on the ball as it whizzed by.
Five minutes after the break, Weimann was at it again as he finished from close range after Agbonlahor drilled a cross in from the left.
Then came the Hernandez show. First he latched on to a sumptuous lobbed through ball from Scholes and threaded the ball through Guzan's legs to reduce the arrears.
Less than five minutes later he met Rafael's cross at the back post with a side-footed volley that was heading wide only for Vlaar to divert it into his own net.
Van Persie hit the woodwork twice - once with a bullet header, once with a long-range strike - but he was still able to set up the winner.
The Dutchman curled an inviting free-kick into the box from 40 yards and Hernandez's superb movement allowed him to steal half a yard and guide the ball into the net.
MAN OF THE MATCH
Javier Hernandez (Manchester United): Showed all his predatory instinct to rescue United from a dire situation - it is just a shame the Premier League's most devastating finisher is not considered worth a regular first-team place.
MATCHCAST: FULL COMMENTARY AND STATS