United and Arsenal have met 12 times in the world's oldest cup competition, and the honours are evenly split, with five wins each and two draws.
The most recent, and arguably most painful, meeting came in the 2005 cup final. Despite dominating for 120 minutes, United failed to break the 0-0 deadlock and lost 5-4 on penalties.
The most memorable, of course, was the '99 semi final replay - Giggs' shirt-swinging celebration after his 109th minute winner at Villa Park indellibly etched in every United fan's mind.