The Mexican, who has scored seven times in the last five games, rescued a United side that had produced one of their worst showings of the season for over an hour but have now won 15 points from losing positions so far.
United traveled to Villa Park without Jonny Evans,as Chris Smalling retained his spot in the starting XI, alongside Ferdinand, Evra and Rafael.
Valencia,Scholes, Carrick and former Villa man Ashley Young – booed incessantly during the 45 minutes he spent on the pitch – formed the midfield, with Rooney and Van Persie up front.
A lethargic first half, in which United wingers’ reluctance to take their counterparts on was nothing short of ludicrous, came to life on the stroke of halftime as Benteke held Smalling off on the left flank, before squaring the ball back to Weimann who buried it past David De Gea to send the home fans Berserk.
For all their 70% possession United had looked completely bereft of ideas and tempo and reemerged after the break with Hernandez replacing Young.
The former Villa man had a bright start to his United career but doubts persist on his ability to make a starting spot his own.
Things were about to get worse before they could get better for United, as they were cut wide open yet again by Villa’s front three, as Weimann tapped into an empty net from close range barely five minutes after the restart, putting Villa inches away from a first league win at Villa Park against United in 17 years.
First, Hernandez latched onto a glorious lofted pass from Paul Scholes before holding off a defender and squeezing the ball through Guzan’s legs.
Five minutes later Rafael’s cross found the Mexican lurking at the back post, from where he side-footed the ball home, albeit via a deflection off Ron Vlaar.
De Gea denied Weimann his hat-trick with a fantastic save, but the tide had turn.
Having restored parity, United pressed on and Van Persie rattled the bar twice within a minute, first meeting a Rooney corner with his head, then with a curling effort from 20 yards out.
Cleverly and Anderson replaced Scholes and Rooney, who looked to have picked up a minor knock, before United, as they had done time again in the past, would attempt at their fans’ health with another late winner.
It came, almost inevitably, from Hernandez, who met Van Persie’s freekick with a diving header after some poor marking from Villa and sparked carnage-like scenes in the United.
The Mexican has rediscovered the goal scoring form of his first season at the club but, having added an immensely improved first touch and link-up play to his repertoire, he could well become even more important to the team.
The dubious goal panel might strip Hernandez of his hat-trick, but United won’t care one bit as they’ve come from behind yet again, maintaining the pressure on City and Chelsea.