The Portuguese winger ambushed Spurs goalkeeper Heurelho Gomes to score United's crucial second goal in the 2-0 win at Old Trafford, after referee Mark Clattenburg waved play on following Nani's claim for a penalty seconds earlier.
Gomes believed Nani had been penalised for handling the ball in the area during an effort to win a spot-kick.
The Brazilian stopper rolled the ball in front of him expecting a free-kick to have been awarded, leaving Nani with the simple task of nipping in and turning the ball into the back of an empty net.
"If he didn't put it in the back of the net, he would have got a bollocking from the manager and the rest of the players," Fletcher told reporters.
"Tottenham will be very aggrieved, maybe rightly so. There was some misunderstanding from the goalkeeper but the ball was still in play."
Earlier in the day, United centre-back Nemanja Vidic scored the 1,000th Premier League goal at Old Trafford and the big Serbian revealed that the players were already spurred on to win by knowing Chelsea's result - a 2-1 win at Blackburn Rovers.
"It is nice to get a piece of history," Vidic said. "But there will be more goals here and I hope this is not my last one either. I try to score and I should get more, so this one is good for my confidence."
United boss Sir Alex Ferguson believes the controversial victory will give his team the confidence they need to mount a serious challenge for the title this season, after stuttering out of the blocks so far.
Ferguson said: "It's kicking-on time. No more dilly-dallying. Chelsea are five points in front and we cannot afford to give any more points away the way we did at the start of the season."
By James Martini
