Arsene Wenger believes that Arsenal's failure over the past few years at Old Trafford was down to the fact that they were too apprehensive, something which they had worked on before this game.
The Gunners secured their first victory away at Manchester United in almost a decade, with their last win coming in September 2006, when they managed a double over their more decorated rivals.
It was a massive win for Arsenal, who can now concentrate on securing a Champions League spot and go all out in their game against Monaco in the second leg of the round of 16 tie in the Champions League.
Nacho Monreal opened the scoring for the Gunners after Alex Oxlade-Chamberlain wriggled past some United defenders and managed to open up the Spaniard. United equalised soon after through Wayne Rooney, but Arsenal dug deep and were the better side in the second half, for which they were duly rewarded with Danny Welbeck's goal.
Antonio Valencia's backpass to David De Gea was latched on to by the former United player and slotted home with aplomb, securing Arsenal's second visit to the semi-finals of the FA Cup in consecutive years.
"It was important for us to start at a high pace, put them under pressure and I think we started without any apprehension. That gave them problems. Unfortunately at half-time it was 1-1 but overall we felt we were in control in the second half after we scored the second goal. We could have scored one or two more. Overall I'm pleased above all with the performance and the mental aspect of the game. It was always positive and you know that I like that," Wenger told Arsenal's official website.
"On the day we have shown that we are mentally on the level that was requested because it was a very physical game, a very committed game where we needed to deal with a very dedicated Manchester United team and we did that well without forgetting to play our football. You need some quality to do that," he added.