The Liverpool skipper was practising free-kicks with team-mate Philippe Coutinho when the unnamed male began directing abusive comments towards him from outside the ground's walls.
Gerrard initially ignored the abuse, but reacted after the comments became personal with the man shouting: 'I know where you live ya p****... I'll burn your f****** house down.
Liverpool assistant manager Colin Pascoe held Gerrard back as he went to confront the man.
The club's kit manager Lee Radcliffe then ran from the field outside the ground to intercept the male, before he fled on a bicycle while shouting: 'I'll kill you and your f****** kids'.