Paul Pogba has been blasted for his "schoolboy" performance against Sevilla by Manchester United icon Roy Keane.

The Red Devils' record signing has found his form under severe scrutiny in recent weeks and has been in and out of Jose Mourinho's starting XI.

Pogba was brought off the bench with the score at 0-0 in Tuesday's Champions League last-16 tie, but looked devoid of confidence – emphasised by a woeful misplaced pass that went straight out of play – as United crashed out 2-1 on aggregate.

Keane believes Pogba's form is emblematic of the problems faced by Mourinho and his squad.

"Pogba, we've spoken about Pogba a number of times. He's not the only problem," Keane told ITV.

"But if he can't get in the starting XI, you're in trouble.

"He comes on, you expect good players to affect the game, he came on and did nothing.

"We saw with the goal, his reaction to it was like a schoolboy. He doesn't smell danger. The reason you're in a team is if one of your mates makes a mistake, you cover for him.

"You make up for him, nobody is helping each other. They're playing as individuals."

The Irishman also took aim at Jose Mourinho's stewardship at the club, pointing to the former Real Madrid and Chelsea manager's skewed perception of what a treble-winning season.  

"The worry for me is that when the manager won last season, they won three trophies, the manager was including the Charity Shield as a trophy - my god, you know you're in trouble."