Rio Ferdinand has expressed his belief that Manchester United boss Jose Mourinho is "testing" Luke Shaw by leaving him out of the team.
The 22-year-old full-back returned to action in the Carabao Cup win over Burton Albion last month, but has since not featured against Southampton, CSKA Moscow and Crystal Palace.
And Ferdinand has claimed that Mourinho is likely challenging Shaw to prove that he is worthy of a place in the first-team.
“It looks like he is testing them mentally,” Ferdinand told BT Sport, quoted by the Independent.
“Hit them with something – are you going to stay down or are you going to get up and fight? If you get up then he says yes, that's the type of man I want in my team.
“As players, that's what you want in your team. You don't want players who will get one hit and shy away from things.
“One bad pass in a game, shy away from taking the ball again for the next 10 or 15 minutes... that's not how you win titles.
“You need players who are going to be brave receiving the ball, not just physically but mentally, and saying whatever happens here going forward, I will be with you guys shoulder to shoulder.”
Mourinho recently called on Shaw, signed for £30m from Southampton in 2014, to "improve".
"He has to work," the Portuguese coach said. "He has to improve. Luke had surgery and a long time without playing. I cannot expect him to be back and strong, strong, strong in his work."