The United player that has gone from boo boy to key man

The Manchester United boss was not pleased when he learned that Fellaini had played for Belgium despite struggling with a calf injury.

Mourinho directed his anger towards Belgium's management staff, but speaking before his side's clash against Basel on Tuesday, the Portuguese tactician was particularly keen to emphasize Fellaini's importance to the Red Devils.

'He's a very important player for me,' Mourinho said before the Group A matchup. 'Much more important than you can imagine. I feel weaker without Fellaini in my squad... I need him'. 

Although initially a doubt for the Champions League opener, the 29-year-old was deemed fit enough to play and ended up being used as an early substitute for the injured Paul Pogba.

He completed an impressive 75 minutes and netted United's first goal in the 3-0 win.

Fellaini's Old Trafford career has taken a number of twists and turns, going from being jeered by his own supporters to one of Mourinho's most reliable midfield enforcers.

United's manager has access to Nemanja Matic, Paul Pogba, Ander Herrera and Michael Carrick in central midfield, but refused to let Fellaini leave this summer despite interest from AC Milan and Galatasaray.