Michael Ballack is uncertain how long he will be sidelined after a right thigh strain forced him off during Germany's 3-1 victory over Switzerland in Dusseldorf tonight.
The Chelsea midfielder limped off the pitch one minute before the break and did not return.
He admitted he was in pain and 'not feeling well' when he left the stadium.
'It is definitely a strain, but I hope it's not serious,' Ballack told PA Sport after the match.
'We have to wait and see in the next few days how the pain is. I hope it does not get worse.'
Ballack feels frustrated by the timing of the injury.
'The injury is annoying for me,' he said.
'I've been getting through the season quite well in terms of injuries, so picking up a knock in a friendly like this is annoying and unfortunate.'