The German FA, DFB, tweeted the news out early on Friday evening, confirming that the 22-year-old had left the team hotel in Munich, where Germany held the world champions on Thursday night.

As a result, he won't be available for Germany's friendly clash with Peru in Sinsheim on Sunday.

Sane was the shock omission from Joachim Löw's final 23-man squad for the World Cup in Russia after winning the Premier League's Young Player of the Year award for an excellent campaign with the English champions.

Some German media have speculated that Sane has left the Germany camp to be with his girlfriend, who is expecting a child. But there is, as yet, no confirmation of this.

The news come shortly after Sane's international teammate Toni Kroos suggested Sane, who was left out of City's last matchday squad, needed to work hard to fulfill his undoubted potential.

"Sane has everything to become absolutely world class," Kroos said. "But one has the feeling that he has to be told what to do to become that. Maybe that's precisely the reasoning in Manchester too. I do not know, I'm not there.

"What's clear is that you have to find a way to get him to his top performance. Then he would be a huge enrichment to us with his qualities, which are relatively rare when you look at our squad."

At this stage, it doesn't look likely that Löw wil call up a replacement for Sunday's game, which may give him a chance to try out a few new tactical ideas.

mp (DPA, AFP)