Germany captain Michael Ballack sustained an ankle injury while playing for Chelsea in the FA Cup final on Saturday, less than a month before the World Cup.
The midfielder won't know until after the results of medical scans on Sunday if he will be fit for Germany's World Cup opener on June 13 against Australia.
"It's not that good at the moment, but I have to wait until tomorrow for the scan and then we will know more," Ballack said. "Hopefully I can play [against Australia] but as you know I went off and couldn't carry on, but it's not that bad."
Ballack went down clutching his right ankle after a challenge from Portsmouth's Kevin-Prince Boateng as Chelsea won 1-0 at Wembley Stadium.
"It's not good in (soccer) when that happens and nobody wants to see it," Ballack said. "He got away with a yellow and was lucky."
Ballack received treatment on the pitch, and went off before returning to the match for a few minutes before eventually hobbling off in the 44th minute.
"We don't think it is a bad injury," Chelsea manager Carlo Ancelotti said. "We hope he will be ready for the World Cup."