United needed De Gea to save Leighton Baines' spotkick to earn the three points.
The Spaniard said: "I think we played a very good game.
"I think in the first half we had the possession and we scored a goal and I think in the last 10 minutes they pressed a lot and they had many chances, but I saved their chances and I'm happy for that, for the win.
"I think the back four defenders for the team played very well and of course it was a great match a good three points."
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