Manchester United manager Sir Alex Ferguson accused Manchester City boss Roberto Mancini of attempting to influence the referees during Monday's derby.
City prevailed 1-0 thanks to captain Vincent Kompany's first-half header to take the club top of the Premier League table, above United on goal difference with only two games each left to play.
The managers had to be kept apart on the touchline by fourth official Mike Jones after a difference of opinion over Nigel de Jong's foul on Danny Welbeck led to angry words and gestures being exchanged.
"He (Mancini) was badgering the referee the whole game, the fourth official and the linesman, and the minute I go out there ... He was complaining about referees all week, he can't be complaining tonight, that's for sure," Ferguson told Sky Sports after the match.
Victorious Mancini played the incident down, adding: "I don't remember (what the row was about). I told the fourth official it was a foul for us, not against.
"At that moment the tension was high, but for me it's forgotten."
The pair shook hands after the final whistle.
