And one player that has not impressed Mourinho is Martial, who has endured an inconsistent campaign.
The story claims, though, that Manchester United would only be willing to consider letting Martial leave Old Trafford if Willian is included as part of the deal.
Jose has always been an admirer of the Brazilian having worked with him at Stamford Bridge after stealing in to sign him from under the noses of Tottenham.More news: Mystery solved: Why Trump-Macron friendship tree vanished
Willian has been a regular at Chelsea since joining the club and has played a key role in recent seasons.
Certain members of the Manchester United squad could well be in the firing lime at Carrington today, with Mourinho now looking to prepare his side to take on West Ham.
Martial's future at Manchester United has been under the microscope after it emerged that the Frenchman is delaying signing a new deal over concerns about his playing time.
It's these moments that you find out how much you really trust the manager - he might be taking a risk, but Mourinho certainly knows what it takes to win league titles.