A new war of words broke out between Arsenal and Manchester United after Arsene Wenger accused Ruud van Nistelrooy of cheating to get Patrick Vieira sent-off.
Vieira was shown a second yellow card by referee Steve Bennet for a petulant kick at van Nistelrooy during Sunday's 0-0 draw after the Dutchman had jumped into him.
The Arsenal players reacted angrily at Van Nistelrooy, pushing and shoving him as both sets of players squared up.
There were more unpleasant scenes after Van Nistelrooy missed an injury time penalty, as Arsenal players surrounded the striker to mock him.
Vieira's kick out at Van Nistelrooy failed to make contact, but when asked afterwards if the Dutchman had cheated in the incident, Arsenal boss Wenger said: "Yes. I think Van Nistelrooy does not help himself frankly.
"He is a great player but his attitude...he is always looking to dive.
"He looks like a nice boy but on the pitch it is not always fair behaviour.
"If Patrick had to go off then Van Nistelrooy had to go off. Patrick is 100% sure Van Nistelrooy caught him.
"Patrick should not have reacted but you punish more the consequence than the source of the problem."
Vieira became the 52nd Arsenal player to be sent off under Wenger, but claimed referee Bennett was hoodwinked by Van Nistelrooy.
The French midfielder said: "The ref got it wrong because of the reaction of Van Nistelrooy.
"I did raise my leg, but I didn't touch him, there were two metres between my leg and his body.
"If the referee had sent me off for kicking him I could accept that.
"But he never gave me an explanation, he showed me the red card. I tried to explain that Van Nistelrooy had made a reaction.
"I can't appeal because it is two yellow cards, but I hope the referee will watch the incident and change his mind.
But Man Utd boss Sir Alex Ferguson leapt to the defence of his star striker.
He said: "I can defend Ruud. I heard Arsene's comment about Ruud after the foul on Patrick. Vieira has reacted badly. Ruud has not dived.
"The referee had no option, no alternative.
"In a ferocious game, I think my players behaved properly."