Hernandez struck 15 minutes from time to help United claim its first top-flight win at Stamford Bridge in over 10 years.
The victory extended United's winning streak to five matches and also narrowed the gap on league leader Chelsea to just one point.
United's defensive frailties, and Chelsea's devastating early-season form, had led many to claim the Blues are better equipped to win the league this season than their Lancashire rival.
So having helped his team stifle Chelsea's comeback with his second-half winner, Hernandez was under no illusions as to how important the three points were to his club.
"This game could have changed the title," the Mexican said.
"That's why it was important we didn't allow them to get ahead.
"It was vital to get the three points at a very tough place. We are in there in the fight to win (the Premier League)."
After a slow start, United has started showing signs it is back to its best.
Ferguson's team has racked up wins against old rivals Chelsea and Liverpool, and midfielder
"It's important to take points off your rivals likes Liverpool, Chelsea and Arsenal next week," he said.
"Next week is just as important. It's a good start to the season.
"We've obviously had a couple of defeats but we've bounced back and we're still in a good position, so we can be happy."
The game lived up to its blockbuster billing, with five goals, two red cards and a series of contentious refereeing decisions that sparked a furious row between Ferguson and the Chelsea bench on more than one occasion.
Then it later emerged that Chelsea had made an official complaint to the Premier League alleging that referee
Clattenburg's decision making, and that of his assistants, proved to be the main talking point directly after the match, however.
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 (
"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
"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."
Ferguson was impressed by Hernandez's killer cameo which may have earned him a place in United's starting XI for Wednesday evening's (Thursday morning AEDT) Capital One Cup clash at Chelsea.
"He's brilliant in there and he took a lot of punishment, too, there were a lot of tackles against him," Ferguson said.
"But he's such a courageous little lad, such a tough cookie.
"He's always going to be a threat to defenders and he's got the winning goal in an important game."
English Premier League