The Red Devils went four points clear on top of the Premier League table despite falling two goals behind early in the second half with Chicharito's predatory skills netting him a possible hat-trick with the dubious goals panel still to decide if his second will be awarded to him.
Not to be forgotten, Villa young gun Andreas Weimann produced a brilliant performance of his own with a double but Paul Lambert's men could not sustain their pressure after finding themselves in an usual position against Sir Alex Ferguson's men five minutes into the second half.
Weimann had Villa ahead in stoppage time of the first half when he fired home a delightful side-footer from the edge of the area after Christian Benteke had skinned Chris Smalling on the left flank which had the Villa Park faithful in raptures.
The Austrian then added to his opener when he managed a neat first-time touch to slot home Gabby Agbonlahor's low cross from the left in the 50th minute.
United are always a chance of getting themselves back into the contest and that comeback began when Hernandez, who replaced former Villa winger Ashley Young at half-time, controlled Paul Scholes' pinpoint delivery from the centre of the pitch before getting a lucky bobble which he slotted through the legs of Villa keeper Brad Guzan in the 58th minute.
Five minutes later, the Mexican pulled United level when Rafael chipped a lovely ball from the right side to the back post for Hernandez to volley goalward with the ball taking a massive deflection off Ron Vlaar.
Hernandez then completed the fightback with three minutes of regular time remaining when he produced a brilliant diving header to nod home Robin van Persie's curling free-kick.
In the 66th minute, Weimann was denied a hat-trick when David de Gea produced a world-class reflex save to keep out his close range header before van Persie hit the woodwork twice within a minute - the first a near post header from a corner which cannoned into the upright before a delightful curling left-footer scraped the crossbar.
The win has United sitting pretty at the summit of English football with second-placed Chelsea to meet Liverpool and third-placed Manchester City taking on Tottenham tomorrow, whilst Villa find themselves dangling above the drop zone with just nine points from 11 outings.
For the statistics enthusiasts, it was the 15th point United had taken this season from losing positons.
Villa Park, Birmingham - 40,538