People can say I'm fat but I've never been out of shape – Shaw ready to silence critics

Manchester United left-back Luke Shaw said he has never been out of shape as he likened his build to former captain Wayne Rooney, while the Englishman has the backing of Jose Mourinho heading into a make-or-break season.

Shaw has struggled to establish himself under United manager Mourinho since the Portuguese boss replaced Louis van Gaal in 2016 – the former Southampton full-back limited to just eight Premier League starts last season.

Perceived weight issues and a poor diet have emerged as possible reasons behind Shaw's failure to win over Mourinho at Old Trafford, with make-shift full-back Ashley Young preferred in the starting XI.

However, the 23-year-old – who is in the final year of his deal – defended his physique and insisted he is ready to win a new contract following a gruelling personal pre-season training routine in Dubai.

"People think because of the way I'm naturally built I'm bigger than I am," Shaw said. "People can say I'm fat but I know my own body. Of course I always look big because I'm bigger built. You could say a Wayne Rooney type of body.

"But of course I worked hard and not just for them [the critics], I wanted to for myself, get in the best shape and that wasn't my best shape. It was a good shape to start the season off, the preseason, but now I'm working harder than ever and first game of the season I want to look 10 times better than I did in that picture.

"I'm working towards that and with the games and training we're doing here. Obviously we've got a new fitness coach and he's working us all hard and that's what I need."

Shaw, who does not want to sign a contract right now as he fights to prove his worth, added: "I guess you've just got to take it [criticism] because there is always going to be negative criticism and positive but I think both of them can make you stronger. And I think I've been unlucky because I've had a few ups and downs with different managers but I would say I've never been out of shape I've just, I don't know, sometimes people don't think I'm fitter than I am but that's all in the past.

"And, honestly, I feel really good and I'm raring to go. The minutes are only going to help me become fitter. That's what I need: minutes and hard work in training."

Mourinho has been critical of Shaw during his tenure at Old Trafford, but the latter insisted he has the backing of his boss heading into a defining 2018-19 season.

"I spoke with the manager about a week after the holidays. I was in Dubai and he texted me and we had a really good chat, it made me feel really confident about the upcoming season and that's why I worked really hard. I want to prove to him as well that I can be here, as well in this team," Shaw said.

Asked if he doubted his future after he was substituted at half-time of United's FA Cup clash against Brighton and Hove Albion last season, Shaw replied: "Not doubts, but there has been emotion. I was very upset but he only does stuff like that because he knows what I can do.

"We've had this conversation. It was literally like two days after. I hadn't spoken to him since. I was very upset. We were training and he spoke with me afterwards and he said: 'It's frustrating to see you like that when I know you can do this.' It's all positive and it's down to me to prove it to him. He said that he knows I can be the best, but he sometimes feels frustrated that I'm not doing that. He knows what I can do. That was one of the texts he sent me in the offseason. 'I know what you can do - you can be the best but you've just got to work on a couple of things.' That's why it pushes me on more.

"He says these things because he knows I can do it. He knows I can be a top player. He knows I can play for Manchester United. It's horrible at times because people only see those things he says [in public]. That's fine because I'm a grown man and I can take stuff like that. I'm used to it. But the stuff inside the training ground, no one sees apart from me. It still gives me confidence."