How many substitutes in FA Cup? Manchester United and West Ham use concussion subs for first time

Issa Diop's clash with Anthony Martial in the first half meant West Ham decided to replace the centre-back at the break using a concussion substitution

Edinson Cavani replaces Mason Greenwood at Old Trafford (Reuters)

West Ham used a concussion substitute for the first time in English football on Tuesday night in their FA Cup tie with Manchester United, in a game in which both teams were allowed to make an extraordinary seven changes in total.

This season teams are allowed to make five substitutions in the FA Cup, via up to three separate stoppages, a decision pushed by the Premier League in order to help manager alleviate the workload of their players and avoid injuries.

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In addition, new concussion rules mean that an extra substitution can be made in the case of head injury. Issa Diop's clash with Anthony Martial in the first half meant West Ham decided to replace the centre-back at the break using a concussion substitution. United were given an extra sub too as a result, meaning both teams could make six changes.

And when the game went to extra time, both managers were given a further change to make, as is the case in cup competitions, making a total of seven possible substitutes from a bench of nine players.

As the FA explains: "Clubs are now able to name a maximum of nine substitutes of which five may be used. Teams are permitted a maximum of three opportunities (excluding half time) to make substitutions during normal time, and with the ability to carry over any unused substitutes and make a further substitution should the tie progress to extra time.

"Clubs competing in the Emirates FA Cup will be able to make additional permanent concussion substitutions. Following extensive consultation with medical experts and national associations to find ways to improve management of possible neurological head injuries in football matches, the International Football Association Board (IFAB) approved trials to use additional permanent concussion substitutes (APCS).

"The IFAB believes that where there is any doubt about a player having been concussed, the player should be protected by being 'permanently' removed from the match and to facilitate this, the player’s team should not suffer a numerical disadvantage by prioritising the player’s welfare. And the FA has agreed to engage in the IFAB trial by applying to use the IFAB Protocol B which allows each team to use a maximum of two APCS in Emirates FA Cup matches from the fifth round onwards in accordance with Rule 15(c)(ii) of the FA Cup Rules.

"As a result, each team is permitted to use a maximum of two APCS from the list of nine substitutes named on the team sheet. An APCS may be used regardless of the number of substitutes already used, but when an APCS is used, the opposing team then has the option to use an additional substitute for any reason."