"It was marvellous, the energy and commitment was absolutely brilliant," Fergie said of Tevez on Sky Sports News.
"I don't think you could ask for a better performance than that.
"Four goals and a very committed performance, and I am very pleased with that."
On the result Fergie added, "It shouldn't have ended up that way with eight goals. We lost three goals in the second half and with the last two there was a lot of carelessness about our play.
"By that time we were enjoying ourselves and there was a sort of carnival atmosphere. We were playing good football, but we could have got a cold there.
"Fortunately, Carlos wrapped it up in the final minute with a fantastic goal.
"We're in the semi-finals and I think we deserve to be in it."