The Scottish tactician said he could not believe referee Olegario Benquerenca did not award Darren Fletcher a penalty when he was seemingly tripped in the area (Benquerenca booked Fletcher for diving) and admitted it was one of the worst decision's he had ever seen.
"I can't believe it. I can't believe the decision. It's one of the worst I've seen in my lifetime," said Ferguson.
Despite the poor decision, United managed to come from behind to record a 3-3 draw at home against CSKA Moscow to book their place in the round of 16 but Ferguson was unsure about the result during a post-match interview with Sky Sports 2.
"I need 10 minutes to think about that. Their goalkeeper made some fantastic saves," he said.
"I thought the intensity of our play, and particularly in the last 25 minutes, was terrific."