Anthony Martial was left 'surprised and disappointed' by Manchester United's decision to take the number nine shirt away from him during the summer, according to the player's agent.

The arrival of superstar forward Zlatan Ibrahimovic from Paris Saint-Germain during the off-season saw the Frenchman swap to number 11 instead.

Martial, who joined United for an initial sum of £36m in August 2015, has struggled to find his best form so far this campaign under Jose Mourinho, which has led to suggestions that he will be sold in the New Year.

Agent Philippe Lamboley has done little to quell the talk of a move away, insisting that his client was 'disrespected' by United when asked to swap jerseys.

"I am not going to lie about it, it hurt him when Manchester United took the number nine jersey off him. He was surprised by it and he was disappointed for a few days," he told RMC.

"But he is a professional. He knew that he had to fight back. Personally, I did not accept the decision, which I thought was disrespectful and misplaced. I let the United hierarchy know how I felt. You do not do things like that. We have turned the page, but not forgotten about it."

Despite the bad blood, Lamboley says that Martial's relationship with Mourinho remains "professional" as he attempts to force his way into regular first-team contention.

"It is not true that Anthony has a bad relationship with Mourinho," he added. "They have a professional relationship. I'm sure Mourinho will get the best out of him, just like Louis van Gaal did before him.

"Anthony is happy at United. We are trying to get out of a bad spell, he is no longer smiling all the time. People who know him know that he likes to smile."

Martial has started four Premier League games for United this season and featured a further three times from the bench, scoring one goal and assisting two others.