It marked Fellaini's first start of the season.
Mourinho said, "Yeah, he's our best player in the air. Despite of Matic, Paul, they are also big guys, Marouane in the air is not just the best for us, probably one of the best in the Premier League.
"He was that cover in front of Victor and Smalling that made a comfortable game for them. There were lots of good performances but Fellaini was fundamental, together with Smalling and Lindelof. Luke Shaw had a good performance and there were many others, too.
"Many thanks to all of you who made the trip to Burnley and cheered us on relentlessly. And, of course, thank you for chanting my name and singing 'my song'! You're all amazing."