Paul Scholes has questioned whether Manchester United defender Luke Shaw is living a 'clean' life as he struggles for game time - although he remains a huge admirer of his talent.

Shaw started for United in their 2-1 Champions League victory over CSKA Moscow on Tuesday - his first time in the starting 11 for 219 days.

The England left back's fitness and lifestyle was questioned by ex-United midfielder Scholes, who compared Shaw to Wayne Rooney in that he may not live the health-conscious way required of top athletes.

Paul Scholes has questioned whether Manchester United defender Luke Shaw is living 'clean'

Shaw started for United in their Champions League clash with CSKA Moscow on Tuesday

Shaw impressed with his attacking runs and pace as United won 2-1 at Old Trafford

Speaking on BT Sport, Scholes said: 'It's difficult to say as we don't see what goes on behind the scenes. I don't think he lives his life as clean as he possibly should do.

'With his body shape, he looks like a player who needs to be playing every week. We had Wayne Rooney, who was a player if he missed a couple of games you knew, he wasn't looking after himself. He needed to be playing all the time, Saturday, Tuesday, whatever it may be.

'With Luke Shaw, is he going to get a run of 10 games in the team? I'm not sure, the problem he has got is that Ashley Young has been brilliant at left wing back.

'I hope there is a future for him. A couple of years ago, I thought we were signing the best left back in the world.'

The England left back's fitness and lifestyle was questioned by ex-United midfielder Scholes

Shaw impressed as he played 90 minutes against CSKA, making several dangerous attacking runs, although he was beaten in the build up to the away team's goal.

Scholes maintained that Shaw is the best player available to Jose Mourinho at left back - but only if he is fully fit.

He said: ‘He is the best left back at the club, he won’t play on Sunday but he showed what he can do.

'He is a flying machine, he got caught a bit for the goal but he is so powerful. I can’t think of a left back who can change a game as quick as he does’.

Scholes' fellow ex-England international Steven Gerrard hopes Shaw can resolve his issues

Scholes' fellow ex-England international Steven Gerrard feels Shaw's absence from the United team under Jose Mourinho is down to issues off the pitch, which he hopes can be resolved soon.

Gerrard said: 'I think Mourinho is doing it for a reason, to try and get the best out of Shaw, he's obviously not happy with certain parts of his game, whether its fitness or his body shape.

'All of us, as England fans, need to see him back playing on a regular basis because when he is on the top of his game he is one of the best left backs around.'