Manchester United "legend" Wayne Rooney deserved the freedom to make the decision over his own future, according to Jose Mourinho.

Rooney left United in July, rejoining Everton having spent 13 years at Old Trafford and, over that time, becoming the club's all-time record goalscorer.

Although Mourinho has previously claimed he would have preferred for Rooney to stay at United, the former Chelsea manager has acknowledged it was an easy decision to let the 31-year-old, who is likely to start for the Toffees at Old Trafford on Monday (AEST), return to Goodison Park.

"I think it is easy. When the legend decides. I think so [it is the legend's choice]," Mourinho said.

"That way it is easy because you don't have to think a lot.

"You just have to respect the player's desire, and what they decide. And when they're a legend they deserve that freedom of choice."

While Rooney's return to Everton has yet to spark Ronald Koeman's side's start in the Premier League, Mourinho's United sits atop the table, having accumulated 10 points from a possible 12 on offer.

However, Mourinho insists that he is not getting carried away by United's impressive opening.

"We have 10 points. Man City have 10 points," the Portuguese added. 

"Chelsea have nine points, Tottenham maybe seven, Liverpool seven, so what's the difference?

"One point, two points, three points, one weekend, two weekends. They also have managers with title histories. Not all in the Premier League but in other countries.

"Everybody has a history of success."