Millwall are facing a six-figure fine after Leicester City made a complaint to the FA about abuse and intimidation suffered by their supporters, staff and players.
League One Millwall’s FA Cup fifth-round win over the Premier League champions on Saturday was spoilt by crowd trouble at The Den and ended with a pitch invasion by thousands of home fans.
The FA will investigate after mounted police were forced to intervene when a Millwall mob tried to reach away fans in the North Stand and missiles were thrown by both sets of supporters.
Sportsmail understands that Leicester insist their players were spat at and abused as they left the team bus and while warming up.