Shaw looks increasingly likely to leave Old Trafford at the end of the season after Mourinho launched another scathing attack on the left-back.
It came after United progressed to the FA Cup semi-final at the expense of Brighton, but Mourinho was far from impressed with Shaw’s performance.
The Portuguese coach publicly questioned the defender’s approach to training last April and has been in and out of United’s side ever since.
Ashley Young has established himself as United’s preferred choice at left-back despite the position not being his natural role.
Shaw is not the only player to have been on the receiving end of Mourinho’s barbed comments.
And former Ireland international-turned pundit Cascarino has claimed the United boss could be risking devaluing some of his squad members.
“Jose Mourinho’s criticism of his team after beating Brighton & Hove Albion was strange,” Cascarino told The Times.
“When United were poor and lost to Seville in the week he dismissed the complaints and when his team reach an FA Cup semi-final he slaughtered them. Surely it should have been the other way around? It can’t be good for the confidence of his players.
“His approach is odd because it also devalues his players.
“He was again critical of Luke Shaw and the left back will almost certainly leave in the summer. But who will buy him?
“United paid nearly £30 million for him but they won’t get anything near that when they sell him.
“Mourinho’s comments don’t just destroy Shaw’s confidence, they also mean any interested club will want a cheap deal no one wants to sign someone so publicly labelled as a failure by another manager.
“Modern football clubs are big business and modern managers should act accordingly.
“They can criticise without doing damage to the club’s future transfer dealings. Mourinho’s approach is unacceptable at a club like United.”