Bayern Munich defender Mats Hummels has indicated that he could retire from playing within the next five years.
Hummels, 28, rejoined the German champions in the summer after eight-and-a-half years at Borussia Dortmund.
The Germany international told a news conference in Qatar: "Generally speaking, it's unlikely that I'll still be playing at the age of 33.
"First I'll have to see if I'm still good enough, and secondly whether I still have the desire."
In October, the 2014 World Cup winner expressed "an increasing desire to go into coaching" when he retires from playing and said he was not excited by the prospect of playing for Germany in the Confederations Cup this summer.
The tournament -- a warmup for the 2018 World Cup -- takes place in Russia during June and July, and Germany coach Joachim Low has indicated he will rest key players.
Hummels added: "I feel like I'm already 33. I wouldn't be upset if I was one of the players that didn't have to play in the tournament.
"Over the last few seasons, especially last year, I played a lot of games -- so a summer off would be a luxury.
"But if the national coach says: 'You are coming with us,' then of course I will come."