A man has suffered a slash wound to the face after "disgraceful" disorder ahead of an FA Cup match, police said.
Crowds clashed in Southwark, south London, before Millwall took on Everton in the FA Cup fourth round.
The Metropolitan Police said on Twitter that they believed the fight was between Millwall and Everton fans.
Video posted on social media shows police attempt to separate two large groups as punches were thrown.
Officers were called to the scene on Hawkstone Road, Southwark, shortly after 4.30pm, and are urging anybody with any information to come forward.