It's a run that stretches back to 1999, the Treble-winning year, with the last replay defeat coming against Barnsley in 1998...
Chelsea 0 United 2, 6th round replay, 10.03.99
In a 0-0 first-leg draw at OT, Chelsea checked United’s run toward Treble glory as the Reds had 24 attempts on goal to the Blues’ four. Three days later at Stamford Bridge the tie was decided by Dwight Yorke’s insatiable brilliance up front and Peter Schmeichel’s defiance in goal. Yorke put United ahead after just four minutes, then Schmeichel frustrated the home side with a series of crucial saves. But Yorkie saved the best till last as his delightful chip sealed United’s progress.
Arsenal 1 United 2 (AET) (N), semi-final replay, 14.04.99
The last-ever FA Cup semi-final replay was perhaps the best. Two teams at the very peak of their powers slugged it out over 120 enthralling minutes of a tie that had absolutely everything. Dennis Bergkamp cancelled out David Beckham's strike but Ryan Giggs famously won it for ten-man Reds with a stunning, slaloming solo effort in extra time.
Exeter City 0 United 2, 3rd round replay, 08.01.05
“I apologise to the fans. They did not deserve that,” Sir Alex said after a dire 0-0 draw at OT in which only young David Jones emerged with credit. Then 11 days later at Exeter’s St James’ Park in front of 9,033 fans (plus those hanging out of the windows of nearby houses), Cristiano Ronaldo gave a United side boasting Neville, Giggs, Scholes and Rooney a 9th minute lead. Plain-sailing, then? Hardly. Exeter provided a few nervous moments before Wayne Rooney confirmed the win on 87 minutes.