London - Manchester City assistant coach Mikel Arteta was left with blood streaming down his face after a bust-up involving up to 20 players and members of staff following the Manchester derby, a report said on Monday.
Media reports on Sunday said Manchester United manager Jose Mourinho became involved in a physical confrontation with City's players after complaining about their celebrations following a 2-1 win at Old Trafford.
Britain's Guardian newspaper reported that Arteta's eyebrow was split open during the melee in a narrow corridor outside City's dressing room and there were unconfirmed reports that another member of Guardiola's backroom staff needed medical treatment.
The corridor leading to the dressing rooms apparently became congested as players and staff made their way through it after the game, and tensions spilled over into pushing and shoving, with Arteta understood to have suffered a cut to the head.
Mourinho reportedly became involved in a row with City goalkeeper Ederson and United striker Romelu Lukaku was said to be involved.
Earlier reports in the Daily Mail and Daily Telegraph said Mourinho had water and milk thrown at him by City's players and was hit on the head with a plastic bottle.
The Guardian said the United manager did not make any reference to what had happened during his post-match media work.
Arteta was being assessed in the City dressing room after being caught in the crossfire, the report said.
The victory, courtesy of set-piece goals from David Silva and Nicolas Otamendi propelled City 11 points clear of United at the top of the Premier League table, further enhancing their status as red-hot favourites for the title.
Mourinho had accused City's players of diving and committing "tactical fouls" prior to the game and afterwards he made an unconvincing claim his side should have been awarded a late penalty when Ander Herrera was booked for diving.
But City manager Pep Guardiola said: "We won because we were better. In all departments, we were better."
The incident at Old Trafford brought to mind the famous "Battle of the Buffet" that erupted after United beat Arsenal in October 2004, when Arsenal midfielder Cesc Fabregas threw pizza at United manager Alex Ferguson.