The former Ajax star said: 'It's a pity that the manager is Mourinho because normally he's an English player you want to give him time and he can then make mistakes.
Jose Mourinho can only hope that Manchester United are as ruthless against Sevilla on Tuesday as he was in dealing with another of his critics before the Champions League last-16 clash at Old Trafford.
"He's very young, he needs games". I have to be honest and give the credit to the people of the academy that were responsible for his formation, and to Mr [Louis] Van Gaal who was responsible for his first season.
Of course, Mourinho was made aware of De Boer's comment at his Monday press conference, and the Portuguese was fairly merciless in his response.More news: Prosecutors will seek death penalty for Nikolas Cruz, Parkland shooting suspect
"Right now, I'm probably not learning the most on the pitch", Rashford said. "But when you draw away even though it's a 0-0 - and that's not an especially good result - but we get to decide the tie at home, we don't have to win three, four, five, we have to win 5-4, 8-7, 2-1, 1-0, not to win the tie be disappointing".
"You can't be depressed around me, I'm always winding him up".
The 20-year-old frontman has been used sparingly by Mourinho this season but marked his return to the starting line-up with a match-clinching double against rivals Liverpool on Saturday. The brace on his Manchester United debut followed by another two on Premier League debut, the Manchester derby victor, an England debut goal and Sunday's double against Liverpool instantly come to mind.
"I think it's his mentality".
"We are not one of the best teams in the competition but when a team arrives in the last eight, anything can happen", added Mourinho.
Paul Pogba remains a doubt with a leg injury picked up in training last week.