About 200 Manchester United fans broke on to the Old Trafford pitch to protest against the Glazer family's ownership of the club.
The fans were removed from the pitch before some got back on to it later.
There also appeared to be a protest outside the hotel where the United players stayed before the game.
Fans gathered outside the ground and scores of green and gold flares - the colours of United's first shirts when they were Newton Heath and the original anti-Glazer protests in 2010 - were set off at 14:00.
The protests follow United's decision, along with five fellow Premier League clubs, to join the European Super League last month before they all pulled out.