The Frenchman revealed that the dressing room was the happiest it has been all season after the last-minute win over Newcastle.
The Red Devils were eight points clear of their local rival with just five games left on the calendar last season, but Roberto Mancini's men fought back to secure the title in dramatic style in the final minute of the final game.
This time around Sir Alex's men have stretched an early lead to seven points, with a late goal handing them victory in a thrilling encounter with Newcastle on Boxing Day, while City was defeated away at Sunderland for the second successive year.
The France international was relieved to pull off the victory, stating it could be a big moment in the title race, while he fears the sack if the team manages to throw away the sizable lead once again.
"It was a crazy match. For football lovers, it was a great match," the 31-year-old told TV channel Canal Plus. "In the end, it was such a great release for us. I have never seen the players so happy in the changing room this season.
"At half-time Sir Alex told us if we could win this game, then we would have a big chance to be champions again. Remember, we were seven points ahead last term and we lost the Premier League with goal difference. If we do it again this season, Ferguson could sack us all!"
United will hope to keep the momentum going in its next few league clashes, as the club hosts West Brom on Saturday before traveling to Wigan on New Year's Day, while City is away at Norwich before welcoming Stoke to the Etihad Stadium.