The Argentine came off the bench to cancel out Hugo Rodallega's opening goal in spectacular fashion, before Michael Carrick netted a cool winner five minutes from time.
United need just one point from their final two games to retain the title, and can do so in front of their Old Trafford crowd against Arsenal on Saturday.
Tevez, who appears set to leave Old Trafford at the end of the season, has been the subject of fevered transfer speculation in recent days, but it was his contribution on the pitch that left United fans open-mouthed.
Having started the match on the bench, the 25-year-old produced an outrageously inventive back flick to turn in a low Carrick ball just after the hour mark.
Tevez has complained about United's reluctance to turn a two-year loan into a permanent deal, but if he had played all season like he has the last two games - he scored a fine goal in the Manchester derby on Sunday - perhaps his future at Old Trafford might already be secured.
The bald truth is that six Premier League goals in 29 appearances are not the work of a £30 million striker. Yet if he does go, this goal will be some parting gift.
On a wet night at the JJB Stadium, United missed a host of chances before Rodallega's opportunistic opener. Wayne Rooney had the best of those in the 10th minute, when he peeled away unmarked in the box to meet Dimitar Berbatov's clipped cross.
Yet somehow the England striker headed wide with Richard Kingson's goal at his mercy.
A minute later a clearly furious Rooney started another attack, and United worked the ball around magnificently through Paul Scholes, Berbatov and Cristiano Ronaldo to Carrick, who lifted his shot just over.
But United were not alone in their profligacy. With less than two minutes on the clock Antonio Valencia nicked the ball past Jonny Evans - still standing in for the injured Rio Ferdinand - and raced clean through on goal.
But the Ecuadorean sent his attempted chip just wide, possibly distracted by the presence of Nemanja Vidic on his shoulder.
Another Evans slip let Rodallega through in similar fashion, and although he got his shot on target from 20 yards it never seriously tested Edwin van der Sar.
There was nothing the goalkeeper could do on 28 minutes, when Rodallega and Vidic jumped for a header, the ball looped up and both players momentarily lost their bearings, but the Colombian reacted quickest and fired a low shot past Van der Sar at the near post.
A livid Vidic thought he had been impeded, and his backchat to referee Rob Styles earned him a stern talking-to. Ronaldo's unhappiness at being denied what he deemed a clear penalty added to United's foul mood, and they left the field for half-time under a collective storm cloud.
The Portuguese was down in the Wigan box again after the break, having lost his balance following a Maynor Figueroa challenge.
Alex Ferguson has grown to tolerate Ronaldo's pouting, but the 24-year-old's histrionics while the ball was still in play and in the Wigan area will not have pleased his manager.
Ronaldo, having scored free-kicks in his last two matches, hit three poor efforts straight into the Wigan wall and produced several other wayward shots.
What seemed like a night to forget came good just three minutes after Tevez's introduction just before the hour.
Carrick drove a diagonal attempted shot in from the right, the Argentine had no time to set himself but did not have to, propelling the ball into the bottom-right corner with a flick of his right boot.
As time wound down, Carrick made another telling contribution. John O'Shea played a low ball to the edge of the box from the right and the midfielder guided a fine left-foot shot into the top-left corner.
