Being a striker, Hernandez was not too bothered about being in an offside position when he scored.
"I don't' care... the referee counted it," the 24-year-old said.
"When Robin (van Persie) shot and (Petr) Cech made a great save I went for the rebound and the ball went to Rafael.
"The first thing was to get along the line of defenders because I thought that was where the ball was going to go. Thankfully I reacted well to it."
The Mexican did show his selfless side, though, by playing down the importance of his contribution to the win.
"It doesn't matter who scores the goals," said the Mexico striker, who has scored three goals in his last two games for United.
"It has been a good week for me. But the most important thing for me is to have the minutes on the pitch and help the team."