The Belgian midfielder was the standout performer as he scored the only goal of the game when his header found the back of the net to secure the Toffees a 1-0 victory at Goodison Park.
Afterwards, United boss Ferguson conceded that Fellaini had been the main reason for his side's loss.
"Fellaini is a handful - he is a big, tall, gangly lad and they just lumped the ball forward to him, that's all they did," said Ferguson.
"They worked from that base all the time and they got a goal from him, so it's justified."
The Red Devils host Fulham at Old Trafford in their next Premier League fixture.