Sir Alex Ferguson accused Manchester City boss Roberto Mancini of "haranguing" the officials after watching Manchester United surrender the title initiative with a damaging 1-0 defeat at the Etihad Stadium.
Vincent Kompany nodded home the winner in first-half stoppage time as City leapt to the Barclays Premier League summit on goal difference. But the game was more memorable for a touchline spat between Ferguson and Mancini in the second half, following Nigel de Jong's foul on Danny Welbeck.
At one point, fourth official Mike Jones was stood between the pair, who were eventually pulled away by members of their backroom teams. "He refereed the game," said Ferguson. "He was out on that touchline the whole game haranguing the referee, the fourth official and the linesmen."
The United manager added: "The minute I come off the bench for a bad tackle by De Jong on Welbeck, he was out again. He can't have it both ways. He's been complaining about referees this season but he won't be complaining tonight that's for sure."
Mancini attempted to play down the spat, insisting it was just the tension of the moment that got the better of his opposite number.
"He doesn't talk with the referee or fourth official? Never?" said the Italian. "I didn't speak with him (Ferguson). He turned towards me and said something.
"For me it is no problem. I can understand. I didn't say anything against him. I was only talking to the fourth official."
Despite his side's second league double over United in 42 years taking City to the Premier League summit, Mancini continued to insist the Red Devils are favourites to win the title.
"United are the favourites," he said.
"They have easy games. They play against Swansea and Sunderland. They are strong teams but at this moment, for United they will be easy. We have two strong games, Newcastle and QPR. One plays for Champions League, the other for relegation. It is important that we are on the top now but it is more important to be there after May 13."