Manchester United and Manchester City fans clashed at Old Trafford last night (12 May) after a bumper crowd attended the Under-21 derby match.
Greater Manchester Police arrested three supporters at the game, which United won 4-0 in front of a swollen gate of 16,708 fans.
An adult male and a juvenile were arrested for assault while another juvenile was arrested for invading the pitch.
Tensions flared after Warren Joyce's side scored the third goal in their rout of city rivals, which saw United starlets Adnan Januzaj and James Wilson each score as United took a commanding lead of the Barclays U-21 Premier League.
Home supporters were seen climbing over a cordoned off area separating fans and charging towards the away end.
Punches were reportedly thrown and police have asked for CCTV footage of the ugly scenes.
The trouble then continued following the final whistle.
Police were seen running up the touchline towards the players' tunnel after reports of problems outside the stadium.
During the 2013/14 season United saw 112 of their fans arrested – 68 at Old Trafford and 43 at away sides' grounds – making their fans the worst behaved in England and Wales.
Rivals Manchester City were the Premier League side with the second-worst record, with 71 arrests.