Jose Mourinho still has plenty to worry about, despite Manchester United's strong start to the season.

The Red Devils have won all three of their Champions League games, and have won seven of their opening 10 in the Premier League, as well as progressing to the Carabao Cup quarter-finals.

However, all is not rosy at Old Trafford, with fans showing their frustration during Saturday's 1-0 win against Tottenham.

Mourinho even vented his own disappointment about the fans' treatment of Romelu Lukaku to MUTV, after the £90m man struggled to make his mark on the game.

United are also without several players through injury, notably Zlatan Ibrahimovic, Paul Pogba and Marcos Rojo.

Another player who is currently on the sidelines is Marouane Fellaini, but the Portuguese's concerns about him are not on his fitness.

Fellaini's contract expires next summer, and he is yet to agree a deal to extend his stay at Old Trafford, having followed David Moyes from Everton in 2013.

Mourinho said he was "worried" about the Belgian's current situation, but he doesn't feel the same way about Luke Shaw, whose contract is also nearing its conclusion.

"I'm worried about Fellaini and not about Luke Shaw because Fellaini finishes his contract and Luke Shaw doesn't," he admitted.

Fellaini has become an integral part of the set-up at United having initially struggled when he made the move from Merseyside.

The Belgian has four goals in eight starts this year, including a brace in the 4-0 win against Crystal Palace.

He's come a long way from being booed by the United faithful last year, after he gave a penalty away against his former club having come on as a substitute, which cost the team two points in a 1-1 draw.

Luke Shaw has made no such comeback, however, and is currently fourth choice left-back behind Ashley Young, Matteo Darmian and Daley Blind.

Mourinho is reluctant to lose any of his squad on free transfers, with six of them in their final year, and wants cash for those who don't feature in his long-term plans.