Liverpool captain Steven Gerrard had to be restrained by the coaching staff after he was threatened by an unnamed man who had broken into the club's Melwood training ground, according to a report.
Gerrard was striking free kicks alongside Philippe Coutinho at goalkeeper Simon Mignolet when a member of the public was alleged to have climbed over the wall of the facility before hurling abuse at the skipper.
An eye witness told the Daily Mail that the man shouted: "I know where you live, you p***k' and 'I'll burn your f***ing house down," before exiting the complex.
Gerrard had to be physically restrained by assistant manager Colin Pascoe as kit man Lee Radcliffe confronted the abuser before he fled.
Liverpool have so far refused to comment on the incident, but are believed to be reviewing security measures.