The draw has since been made and the winner of the Stamford Bridge replay will take on Manchester City in the last four.
Below, Sports Mole picks the bones out of a thrilling match at Old Trafford.
On target 5
On target 11
Was the result fair?
Yes. United began like a steam train but Chelsea were brilliant from around the half-hour mark. In all honesty, had Chelsea not been so sloppy early on then they would have deserved to win the game.
They were out of the blocks very quickly but United won't be happy with their overall performance. Chelsea made them look like the away side in the second half. Sir Alex Ferguson's side will want to get the win in the replay more than ever as they know City wait in the semi.
The Blues were straight on the back foot but made a fantastic response towards the end of the first half and all through the second. A draw was the least they deserved.
Sports Mole's man of the match
Juan Mata: The diminutive Spaniard was rested for the Europa League loss in Bucharest in midweek and Chelsea paid for that. He started today and although Chelsea begun badly, Mata was the orchestrator of their superb fightback.
Howard Webb had a solid game all round, making no blunders to speak of.
United: Next up for the Red Devils is a home match in the league against Reading on Saturday.
Chelsea: The Blues, meanwhile, welcome Steaua Bucuresti to Stamford Bridge on Thursday needing to overturn a 1-0 deficit from the first leg last week.