West Ham make first concussion substitution as Diop replaced in FA Cup tie

Issa Diop was replaced by Ryan Fredericks after suffering a head injury during West Ham's FA Cup loss to Manchester United on Tuesday.

West Ham make first concussion sub as Fredericks replaces Diop

West Ham United made the first concussion substitute in English football during their 1-0 FA Cup fifth-round defeat to Manchester United on Tuesday.

Fredericks replaces Diop after clash of heads with Martial

Issa Diop - himself an early replacement for the injured Angelo Ogbonna at Old Trafford - clashed heads with Anthony Martial towards the end of a goalless first half.

Ryan Fredericks emerged for the second period and West Ham announced via their Twitter account that the change was a concussion replacement.

Last month, the Premier League and the Football Association approved a trial allowing teams to make a maximum of two additional substitutions in the event of players suffering head injuries and showing symptoms of concussion.

Last weekend was the first time Premier League clubs had the option of making such changes, although none were required.

Concussion substitutions also allowed in Club World Cup

Teams participating in the Club World Cup can also make concussion substitutions, although FIFA is allowing just one additional change.