Manchester United's players may have been in the wrong ahead of their clash with Chelsea groundstaff on Saturday.

United's players are believed to have broken a Premier League rule on warm-downs by running across the penalty areas at Stamford Bridge after Saturday's 2-1 defeat by Chelsea.

Their decision to ignore requests not to run across the 18-yard box helped spark a mass scuffle between United's players and Chelsea groundstaff and stewards.

It is understood players can only warm-down for a total of 15 minutes after a game and they must keep clear of the penalty areas.

Both Chelsea and United have been asked to supply the Football Association with statements relating to the incident and the players and staff involved could face disciplinary action.