De Boer is not the only pundit to question Mourinho's conservative approach when it comes to Rashford who is vying for a starting place alongside the likes of Romelu Lukaku, Anthony Martial and Alexis Sanchez.
"Mourinho is not like that, he wants to get results".
De Boer added: "He can make mistakes but Mourinho is not like that and if he has one or two not good games then he puts him out".
Despite featuring forty times for United this season, Rashford has struggled for starts with Saturday's derby against Liverpool being the striker's first of 2018.
This comment clearly got under Mourinho's skin, and he fired back with interest, taking care to mention De Boer's short-lived and disastrous tenure as Crystal Palace manager earlier this season. What he was saying was not good for Marcus Rashford to have a coach like me because the most important thing for me is to win.
"I try to give the best to the kid's education". "My first goal gave me the confidence to do more".
It's absolutely brutal from Mourinho but it's actually impossible to argue with his assertion that the former Inter Milan manager is the worst manager that the Premier League has seen, statistically at least.
"But if you go to his numbers and how many games he played with me". We have a game on Tuesday and I can imagine, if we lose against Sevilla, everybody will forget what we did in the past couple of weeks. We won 2-1 against Liverpool and at the end of the game there were some who said it was a failure.
Mourinho praised his player in the post-match press conference and admitted that the academy product had previously suffered with confidence issues. "In the last eight you start smelling the semi-finals".
"I don't think we're candidates to win the competition".
Paul Pogba has an outside chance of being involved after he missed the Liverpool game with a gashed leg.