Liverpool face the prospect of extra-time and penalties tonight, should their FA Cup replay against Shrewsbury Town end in a draw after 90 minutes.
While competitions such as the EFL Cup and the EFL Trophy have dispensed with extra-time, it is still played in the FA Cup.
Replays have been scrapped from the fifth round stage, but Tuesday night's fourth round replay at Anfield could go all the way to penalties if required.
Liverpool news and transfers LIVE - FA Cup team news and build-up
The FA Cup rules state: "When a replayed match is drawn after 90 minutes, an extra 30 minutes shall be played, and 15 minutes shall be played in each half.
"If the score is still level at the end of extra time, the winner shall be determined by the taking of kicks from the penalty mark in accordance with the procedure adopted by the International Football Association Board."
But if the game was to require an additional 30 minutes, then the Reds would be able to make a fourth substitution.
"In the event that extra time is played in any match a Club may at its discretion use one additional substitute player, (a fourth in total) from the nominated seven substitutes, during such period of extra time," the rules state.
The winners of the match at Anfield tonight will face a fifth round away tie against Chelsea at Stamford Bridge, scheduled to take place on the week commencing March 2.
