The striker was introduced by Sir Alex Ferguson at half-time and was at the heart of all three of his side's goals as the Red Devils sealed a 3-2 win over Aston Villa
An Andreas Weimann double gave the Villans a 2-0 lead but the Mexican striker, who came on in place of Ashley Young at half-time, inspired a comeback win.
He struck just eight minutes after the Austrian's second before forcing the ball in off Ron Vlaar and then completing the turnaround with a headed finish three minutes from time.
But the forward has insisted he never expects to come on and make such a significant impact.
"To be honest, in my mind I never think that I’m doing it to change the game or something like that," he told ESPN.
“The only thing in my mind is to do my best, to do the things the gaffer told me to do and help all my team-mates with the effort to comeback because we were down 2-0 and thankfully we won.”
The 24-year-old also hopes to be awarded his side's second goal and subsequently a hat-trick, despite the heavy deflection off Vlaar.
“Of course [I will claim it],” the Mexican said. "I think that I hit the target and then the defender touched the ball, but I don’t know that’s the decision of the referees.”
Hernandez went on to express delight with his third goal in particular, given it sealed the three points for the visitors.
“Sure, it’s really special. A wonderful cross from Robin van Persie, and thankfully I can get away from my defender and I head the ball and thankfully it goes in," he added.
“The most important thing is the three points, it doesn’t matter who scored the goals, who’s the man of the match, the most important thing is that Manchester United are top of the league and we came back from 2-0 down and it’s a good result.”