Manchester United's home game against Liverpool was delayed after about 200 fans broke into their Old Trafford stadium to protest against the Glazer family's ownership of the club.
United fans got on to the pitch to protest and, after they were removed, some got back on to it later on.
There also appeared to be a protest outside the hotel where the United players stayed before the game.
Both clubs have submitted their team line-ups for the fixture but neither are yet at the ground.
The Premier League said on its live blog: "After the security breach at Old Trafford, we can confirm the Manchester United v Liverpool match will not kick off at 16:30 BST.