Ruben Loftus-Cheek
Jose Mourinho was far from content with Ruben Loftus-Cheek's performance in a friendly against Sydney FC Getty Images

Chelsea midfielder Ruben Loftus-Cheek has responded to criticism from Jose Mourinho, insisting he must do better and work hard if he is to successfully break into the first-team set-up at Stamford Bridge.

The talented youngster, who made his debut against Sporting Lisbon in the Champions League last season, has been a pivotal figure in the club's youth teams and made his first Premier League start during the 1-1 draw with Liverpool on 10 May before featuring for 73 minutes of a surprise defeat against West Bromwich Albion at The Hawthorns.

Loftus-Cheek was introduced as a first-half substitute as Chelsea travelled to Australia for a post-season friendly against A-League outfit Sydney FC in May, yet subsequently incurred the significant wrath of Mourinho, who described the player's performance as "unacceptable" despite the presence of back problem.

"Loftus-Cheek was saying he had a pain in his back," Mourinho said after the 1-0 win. "But what I was feeling was that he only had this pain when Sydney had the ball.

"When Chelsea had the ball I never saw a pain in his back. When Chelsea had the ball he was playing very, very well. But when Sydney had the ball I think he was more impressed by watching [John Obi] Mikel and [Nemanja] Matic work, instead of himself.

Mourinho even went as far as to confirm his relationship with Loftus-Cheek had suffered as a result of such a disappointing performance. He added: "With Ruben, it is one step back in my relations with him. If he doesn't know what it is to play for me and Chelsea, it's one step back."

Far from being discouraged or disillusioned as a result of that rather harsh assessment, though, the 19-year-old claims he has taken those words on board and has vowed to benefit from Mourinho's vast experience.

"I listened to what the manager said and I wasn't at the level I need to do better, and I need to do better if I want to play for Chelsea," he said, as reported by The Mirror.

"For me that is a reminder that I have to work hard to get in the team. I just need work hard and do my best. I will listen to him and learn from him every way I can. I really want to work hard now."

Chelsea captain John Terry has previously vowed to talk to his inexperienced teammate and called for him to take such criticism "on the chin" as part of a necessary learning curve.

Loftus-Cheek is on international duty with England at the Uefa European Under-21 Championship. An unused substitute against Portugal earlier in June, he made his debut for Gareth Southgate's side with an impressive late cameo against Sweden at the Andruv Stadion in Olomouc.