The Scottish midfielder's substitute appearance in the second half at Villa Park was his first senior outing since Boxing Day in 2012.
After battling ulcerative colitis, a chronic bowel condition, the 29-year-old has worked his way back to fitness and was available for a place on the bench in United's 3-0 win in the West Midlands.
"It was a special moment for everyone and for Fletch, I was really waiting for him to come back," the Brazilian defender told MUTV. "He's helped me a lot since I arrived at the club, he's one of my biggest friends here. He's such a good player, and a good guy - I'm glad he's back."
"You can see with the way he runs for the other players and the way he played, everyone needs a player like him. He's got his fitness back and has been playing for the reserves, he's been coming back slowly but I hope he can now play as many games as possible."
The win at Villa also featured Danny Welbeck playing as a central striker and he scored his first Barclays Premier League goals since the opening day of the season. The first of his efforts followed a fine cross from Rafael that Adnan Januzaj headed against the post before Welbeck pounced on the rebound.