The FA Cup is planning to allow a fourth substitution during extra time from the quarterfinals onwards as part of a test for a proposed law modification.
The change, which is subject to approval from the International Football Association Board (IFAB), will see teams who have made all three changes during the 90 minutes of a quarterfinal, semifinal or final tie permitted one additional switch during extra time.
The idea of a fourth substitute was first tested at the Copa America this summer, though only the final had an extra-time period and both Argentina and Chile made just three substitutions.
Football Association chief executive Martin Glenn said: "The Emirates FA Cup is renowned for its great history and tradition but, as the game's governing body, it is important The FA continues to look at how it can further add to the drama and spectacle of a competition loved by millions around the world.
�� Clubs in the sixth round, semi-final and Final of this season's #EmiratesFACup can make a fourth sub in extra time https://t.co/Xam7sEJ9xN
- The Emirates FA Cup (@EmiratesFACup) July 27, 2016
"With The Cup now adopting a straight knockout format from the quarterfinals onwards, the introduction of a fourth substitute in extra time will bring extra intrigue and interest.
"Also, from a technical point of view, it will be interesting to see how managers use the chance to make an additional substitution in such high-profile games and the impact it has on the final result.
"Player welfare and being mindful of the number of games people play at the elite level has also been a consideration."
Replays have been abolished at the quarterfinal stage in response to increased fixture congestion. Last season, the quarterfinal replay between West Ham and Manchester had to be scheduled at the same time as Champions League ties, which is against UEFA regulations, as there was no other time for the match to be played.
A total of 736 clubs have entered the FA Cup, which begins on Friday, Aug. 5 with 184 extra preliminary round ties -- with ties including Sholing s. Bournemouth Poppies FC. League One and League Two clubs enter in the First Round Proper on Saturday, Nov. 5 with Premier League and Championship sides joining two rounds later on Saturday, Jan. 7.