Roy Keane has said Paul Pogba "did nothing" when he came off the bench in Manchester United's Champions League defeat to Sevilla and is a "problem" for the club.

Pogba failed to provide the spark United needed as they crashed out of Europe's major club competition, losing 2-1 in the round of 16 at Old Trafford.

And former United captain Keane told ITV that manager Jose Mourinho faces a challenge to get the best from the club's record signing.

"He's not the only problem,'' he said. "But he is a big problem and if he can't get in the starting XI you're in trouble.

"He's come on and you expect good players to affect the game. He came on and did nothing. His reaction to the goal is like a schoolboy. He doesn't smell danger.

"The reason you're part of a team is that if one of your mates makes a mistake you cover for them, you make up for it.

"Nobody is helping each other. They are almost playing like individuals and not playing as a team."

Keane said he felt some of United's players were not up to the required standard and did not seem to be relishing the challenges that playing for the club poses.

"When I played for Manchester United, I always felt, when you put on the jersey, you felt great and you enjoyed the history and the pressure and the badge and the expectation from supporters,'' he said.

Paul Pogba shows his disappointment as Manchester United crash out of the Champions League to Sevilla. Simon Stacpoole/Offside/Getty Images

"I get the impression that, this United team, they don't seem to be enjoying the pressure or the expectation.

"The manager will take responsibility. When you see him interviewed after the game, I don't think he was shocked because he's working with the players every day.

"He knows they are short to be one of the best teams in Europe. He knows that.

"Manchester United have had trouble the last three or four years and they need some more players, and I know some people will say that's not always the answer, especially if he's a great coach.

"You've got to work with what you've got and they are short three or four players.

"Some of the players playing for Manchester United now aren't good enough but it's not their fault.

"If you're selected, you're going to play for United but they are short at the top level and their record in the last three or four years will tell you that."

He added that Mourinho's team "are not playing like the great Manchester United teams and that was that even on an off night you can grind out a result. This team doesn't seem capable of doing that."