Dougie Freedman masterminds a historic win against Sir Alex Ferguson's charges to earn a place in the semi-finals
It was a game in which Palace refused to back down, as their heroics in extra-time saw them pull off one of the shocks of the season.
The game will be remembered by a Darren Ambrose screamer from almost 40 yards, but a persistent United equaled the tie minutes later as Federico Macheda earned a penalty before successfully dispatching the spot-kick.
Dougie Freedman’s side successfully pulled off the upset eight minutes into extra-time as Glenn Murray headed in from close range from a free-kick.
United boss Sir Alex Ferguson, despite making wholesale changes, fielded a stronger team than expected. Fabio da Silva was the only United player to retain his place, however, Dimitar Berbatov, Chris Smalling, Antonio Valencia and Ji-Sung Park ensured a strong line-up.
With half an hour played, the game was evenly poised, with both teams attacking on the break and sharing a similar amount of possession.
Zaha, who caused Ferguson’s men non-stop problems throughout the half, had a penalty claim 10 minutes before half time. A through ball by Stuart O’Keefe saw Zaha trip over Darron Gibson’s foot but the referee allowed the game to continue.
A minute later, Fabio was replaced by Ezekiel Fryers after the Brazilian picked up a knock to his hamstring. And, for Palace, Scannell was substituted for Jonathan Parr as the half ended goalless.
The pendulum had clearly swung in United’s favour as they dominated the first 20 minutes of the second half. Morrison continued to inject life into the United attack and had a shot blocked by the legs of Price following a through ball by Park.
Despite dictating the tempo, Manchester United were soon humbled when a wonder strike from Ambrose from 40 yards rocketed into the top corner of Ben Amos’ net.
However, two minutes after Palace went a goal up, United levelled the score after Macheda went down in the box after having his short pulled by Patrick McCarthy. The Italian stepped up to take the penalty he had earned and calmly sent Price the wrong way to level the proceedings.
After an action-packed 10 minutes which culminated in the two goals, the game settled down. However, United continued to permeate the Palace half albeit failed to create any clear cut chances.
Zaha had a relatively quiet second-half but came to life in final moments. After 90 minutes, the game was level as the two teams freshened up before returning for extra-time.
After the brief hiatus, United looking the less lethargic of the two sides as they continued to mount the pressure on their opposition.
Palace then shocked Old Trafford for the second time of the night as they restored the lead through a Murray header. Zaha tricked his way past Park on the left flank and, after the South Korean brought down the Palace striker, the 19-year-old delivered a scintillating free-kick which Murray headed in from two yards out.
United almost replied instantly as Gibson hit a sweet struck volley inches wide of the post. Palace, unwilling to depend on their lead, pushed for another goal: Ambrose hit a fierce free-kick from a similar distance as his second half screamer but was matched with an impressive save by Amos.
The remainder of extra-time proved to be a nail-biting affair as Palace held on to their lead and ensured a momentous victory.