"I'm taken aback that Mainoo hasn't seen more action for United this season, given their midfield woes," Murphy penned for the Daily Mail. "Of course, I understand he's had his fair share of injuries, but come on!"

"Now, Amorim might have his reservations about Mainoo's defensive work, but that's par for the course for a young midfielder adapting to the Premier League and juggling various roles in United's setup," he continued.

"Amorim's tactical approach has done Mainoo no favors. Playing central midfield in a 3-4-3 is no walk in the park – it demands a level of discipline and stamina that's off the charts. It's clear Amorim favors Casemiro and Manuel Ugarte over Mainoo, given their prior history together at Sporting Lisbon," Murphy added.

"But I just don't get what Amorim's beef is with Mainoo. I reckon he's more than capable of shouldering the defensive duties. He just needs a bit of guidance and some seasoned pros around him to help him grow," Murphy concluded.