The France international struggled to find a consistent performance level during Mourinho’s two-and-a-half seasons in charge of the Old Trafford outfit.
Martial impressed in his first season at the 20-time English champions under Louis van Gaal following his £36m switch from Ligue 1 side AS Monaco.
The French star finished with 16 goals in all competitions at the age of 19, but Mourinho used the former Lyon forward sparingly throughout his tenure.
Martial has been regularly linked with a potential move away from Manchester United over the past couple of seasons.
The 23-year-old finished the 2018-19 Premier League season with 10 goals and two assists in 27 appearances in the English top flight.
Asked during an interview with L’Equipe about whether his difficult relationship with Martial was comparable to working with Karim Benzema at Real Madrid, Mourinho replied:
“With Karim it was not a conflict.
“I just wanted to help the player – an incredibly talented player – change his mindset, help him reach his maximum. To become a killer, a determined striker. I really enjoyed working with Karim.
“He [Martial] is a boy with a different personality. The thing I can say is that I hope he will reach a level that is as good as his real potential.”
Manchester United lost 2-0 to Cardiff City in their final Premier League game of the season.
The Red Devils finished in sixth place in the table to qualify for the Europa League.
Manchester United ended the season without silverware for the second successive campaign.
Mourinho was sacked in December following a 3-1 loss to Liverpool FC at Anfield.
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