The former Red Devils starlet opened up about his experiences of working under former boss Jose Mourinho at Old Trafford.
Callum Gribbin, who came through when Louis van Gaal was manager in 2015, did not get many first team chances under Mourinho.
“I used to think, ‘He’s not a***d, is he? He doesn’t even care about getting to know my name’," Gribbin told The Athletic.
"I look back now and I know I shouldn’t have got p****d off about it. But at the time, it used to get to me that I’d go out for training and he wouldn’t even watch.
“He’d be speaking to his staff or on the phone and I used to think, ‘I’m here, I’m trying to get a chance and he’s not even interested’. If I did say something to anyone, he’d be looking at me like, ‘You can’t be having a go, you’re an 18-year-old training with the first team’.
"But in my head, I was thinking, ‘No, I want to get a chance here’. So there were a few issues with Mourinho and other staff. Little things, just building up.”