The Mexican forward followed up his Champions League double with a game-winning goal at Stamford Bridge, although replays showed he was offside.
On the heels of a brace that led the Red Devils to a 3-2 come-from-behind victory over Sporting Braga in the UEFA Champions League, Chicharito came off the bench to score a controversial game-winner in a 3-2 league victory over nine-man Chelsea.
Chicharito redirected a Rafael cross at the goal mouth to restore Manchester United's lead after the club blew a two-goal advantage on the strength of a David Luiz own goal and a Robin van Persie finish.
Chicharito entered as a 65th-minute substitute for Tom Cleverley and made his mark 10 minutes later. After a Manchester United shot hit the post, he emerged from inside the net and tried to scramble back into an onside position to get on the end of Rafael's cross. Replays showed he was even with goalkeeper Petr Cech at the time of the cross but behind the rest of Chelsea's back line.
The result brings United into a tie for second place with rival Manchester City, and both are just a point behind Chelsea through nine Premier League games.