He was handed the shirt following his £36m move from Monaco in September 2015, but was forced into taking the No.11 following the big Swede’s arrival at Old Trafford.
The Frenchman scored 17 times during his debut campaign in England and has struggled for form under Jose Mourinho, with his agent, Philippe Lamboley, claiming the shirt change has affected Martial.
“I’m not going to lie to you. Yes, it got to him. Yes, it surprised him. Yes, he was disappointed… for two days,” he said.
“But he’s professional. He knew how to get back into things straightaway. Personally, I find that decision out of order and disrespectful to my player. I told Manchester United’s board that. You just don’t do it.
“So we accepted it, we turned the page, but we didn’t rip it up.
“He is very happy at United. He is not smiling all the time but that’s part of his personality. People who know him well know that he is a smiling, open and warm guy. He is very attached to the fans who have welcomed him so nicely.
“He has only one ambition: to have a great season and win titles with United. What he has accomplished already is amazing, he is only starting his career. And I promise you the best is to come.”
He has scored just two goals in 12 appearances this season and hasn’t been anywhere near as threatening in attack than he was last season under Louis van Gaal.
There is still plenty of time left to the season and hopes are Martial is able to find his feet at Old Trafford, which should hopefully propell him back into Didier Deschamps’ French side.