The Stamford Bridge outfit are now third in the Premier League following the triumph, which pleases the Spaniard.
"This kind of game when you play for something like us is difficult and to be composed when you have chances is not easy," Benitez told talkSPORT.
"I enjoyed the game because the team had the balance and control. To play against them and beat them at Old Trafford is something you enjoy.
"You are normally expecting players like Juan to make the difference and he did it and I'm really pleased because he's an important player for us."
Chelsea face Tottenham Hotspur on Wednesday.