New rules brought in for this season’s tournament mean all ties from the fifth round onwards will now be decided on the day, but that hasn't been the case in the past.
In fact, nine of our previous semi-finals and two finals – in 1983 and 1990 – have gone to a second game, including the 1970 semi-final against Leeds United that was memorably decided at Burnden Park after two goalless draws.
A countdown of United's 10 greatest FA Cup replays is featured in Wednesday's edition of United Review, which fans buy at Old Trafford or online.