The Russian side held a 3-1 lead heading into the final 10 minutes at Old trafford.
“The chances we made you have to say their keeper has made some fantastic saves,” Ferguson told Sky Sports.
“We lost three goals at home and you don’t like that. It was a surprise the third one after half-time and that gave them something to hold on to.
“I thought the intensity of our play, particularly in the last 25 minutes, was terrific.”
Ferguson continued: “I don’t know how many chances we did create, but it’s something about United, just the history.
“We went for it and risked everything to get the result. I think we deserved it.”
