Ex-Liverpool player and manager Graeme Souness has claimed that Mainoo should be a rotation option.
The teenager started and scored in their FA Cup final win over Manchester City in May and starred at Euro 2024 for his nation.
Speaking after United lost 3-0 to Liverpool with Mainoo in midfield, Souness said: “I have to say this, I'm not being unkind, Mainoo might be a player, but it's so Man United.
“This is not to be critical of Man United, it's never been any different.
“But when someone comes on the scene at Man United, in my days they were the 'new George Best', or the 'new Bobby Charlton', the 'new Denis Law'.
“It is FC Hollywood, they call Bayern Munich in Germany 'FC Hollywood', that's Man United here.
“If anyone shows anything, they're put into superstardom category, way before they've even become a good player.
“And Mainoo right now should be a player that's flitting in and out of a good team - not coming in and being asked to stand up and play against the very best teams.
“He might be a player one day, but he's certainly not the go-to man at United like they're making him out to be in midfield.”