Real Madrid midfielder Toni Kroos has said that Manchester City attacker Leroy Sane must "work on himself" in order to become "a world-class player".

Sane was controversially left out of the Germany squad for the 2018 World Cup despite scoring 14 times and registering 19 assists in 49 appearances for City last term.

The 22-year-old has only played 30 minutes of Premier League football this season, meanwhile, amid concerns over his attitude.

Sane has earned a recall to the Germany squad for their upcoming games against France and Peru, and while Kroos has hailed his international teammate's quality, the midfielder admits that the winger's temperament needs work.

"He can be a world-class player, but he needs people who tell him what to do from time to time and to work on himself," Kroos told reporters. "That's what Pep is doing at the moment with not selecting him. He wants to provoke him a bit.

"It is clear that you have to find a way to bring him to his top performance. If he is at his top performance, he is for us – with his qualities, which are relatively seldom if you are looking at our squad – a player who enriches us. He gives us definitely more options for our game, but obviously only if he is able to show that on the field."

Germany will take on world champions France in their UEFA Nations League opener on Thursday night.