David Moyes brought Fellaini to the club during his time at Old Trafford and the Belgian international has become a key squad player under Louis van Gaal and Jose Mourinho.
Moyes always believed that the midfielder would play an important role for the Red Devils, after he signed him from Everton for £27.5million.
'He was never someone who was going to play in all the games at United. He was someone that was there, his size is a problem to the opposition, it's also something which helps you, Manchester United you've seen many times now have used him a more advanced role.', he said.
'He's a modern day footballer, he covers a lot of ground, he's a decent passer without being a great passer, he can get you some goals, he helps you out in both boxes with his stature and he was something which we didn't have at Manchester United and he was a player who was brought in to add to the squad', Moyes added.