The Frenchman arrived at Old Trafford last year as a relatively unknown talent from Monaco on deadline day, but enjoyed a spectacular debut campaign at Man United.
He scored 11 goals in 31 Premier League appearances last season, despite being played out on the wing for the majority of the campaign.
Speaking about his time at the club, Martial revealed Louis van Gaal helped him drastically improve his game in England.
“I had a great relationship with Van Gaal,” he said.
“He always demanded perfection from me. He has done a lot for me.
“He always showed me videos together with his assistant, even when I had scored a double. He pointed out the things I had done wrong.
“Sometimes it was annoying because you expected to be shown the things you did well, but I knew it was for my own good.”
“Mourinho is a great coach,” he added.”He has won a lot of titles.
“I do not really know him personally yet, but I know how much he has won.
“I know that Mourinho has worked with great players and he helped them improve and develop.”
Van Gaal made Martial’s move to Man United possible so it’s normal for him to be upset over his departure after they built a great relationship together.
The Dutchman’s failure to qualify for the Champions League was the final nail in his coffin, but insisted his successor would be the one to get the full potential out of Marital.
He is still young at 20 and has plenty of time to develop at Old Trafford, he has shown Mourinho his talent and bagged two assists in the opening game of the Premier League against Bournemouth, he will now be hoping to continue his form against Southampton, where he will be playing alongside Paul Pogba and Mourinho’s new signings.