Manchester United players have accused Chelsea staff of provoking a brawl at Stamford Bridge by abusing defender Patrice Evra.
The aftermath of the Blues' 2-1 win on Saturday saw scuffles between United substitutes and ground staff and stewards.
United stars Evra, Paul Scholes, John O'Shea, Gerard Pique and Gary Neville were taking part in a warm-down on the pitch when they were asked to move by ground staff.
A scuffle erupted, in which fellow substitute Carlos Tevez also became embroiled.
The Argentina striker said in The Guardian: 'Patrice received a grave insult from a member of Chelsea's staff.
'He demanded an explanation and, from that moment, these men just wanted to attack Patrice.
'Obviously it's normal that we tried to defend our team-mate but within a few seconds all of the United players were surrounded by stewards.'
Chelsea are to examine CCTV footage of the incident, which the Football Association have asked to see before 'considering the appropriate course of action'.
Tevez said: 'I think that the security cameras will show the provocation we received. I have never seen anything like this in my career... if the FA opens an investigation, we will cooperate and happily give our version of what happened.'
Defender Pique added: 'Basically, this came about because of the provocation of somebody who works for Chelsea.
'Patrice wanted an explanation but these men were very aggressive. All we were doing was finishing our work-out after the game.
'Even now, I just do not understand the reaction of these people. I have seen the photos and, if the images are stored in the CCTV cameras then it will be impossible for them to say that the players were not provoked.'
Tevez added: 'We noticed a hostile atmosphere during the match. That is normal but never did I believe these incidents would happen afterwards without any spectators in the ground.'
Since confirming they would look into the incident, Chelsea have not commented on the matter but one of the men allegedly involved in the fracas, groundsman Sam Bethell, played it down.
'It was handbags really,' he said in The Sun. 'It was not as bad as it appeared.
'I've been told not to say anything about what actually happened.'
Saturday's referee, Alan Wiley, has confirmed he only became aware of the trouble when he watched highlights of the game later that evening.
He said in the Daily Mail: 'With me being in the changing room, I didn't know anything about what might have happened after the match until I saw `Match of the Day'.
'The security people said they had nothing to report to me. The players from both teams worked really well with me.'
Wiley came under fire from United boss Sir Alex Ferguson for awarding Chelsea the late penalty which won them the game.
Ferguson branded the decision to penalise Michael Carrick for handball 'diabolical'.
But Wiley said: 'If there is a penalty shout, the team on the receiving end will be disappointed.
'But if they sit down and look at it, they'll accept that it was a penalty.'