Ryan Fredericks became the first concussion substitute in English football when he replaced Issa Diop in West Ham’s FA Cup tie against Manchester United.
Diop clashed heads with Anthony Martial late in the first half at Old Trafford. Under new rules which were introduced on February 6, clubs are able to make up to two additional substitutions in the event of head injuries and Fredericks replaced Diop at half-time.
The Premier League and the FA announced trials of concussion substitutes in January following approval from football's lawmakers, the International Football Association Board.
Teams are allowed five normal substitutes in the FA Cup. Fredericks did not count as one of those five for West Ham.
Diop will now have his head injury assessed. The defender was himself a substitute when he replaced Angelo Ogbonna after 16 minutes when the Italian twisted his ankle.
West Ham face Sheffield United next Monday, and losing Diop and Ogbonna is a concern for Hammers manager David Moyes.
