Lukas Podolski and Torsten Frings are both doubtful for Germany's Euro 2008 quarter-final against Portugal on Thursday, coach Joachim Loew said on Tuesday.
Podolski took a knock to his calf and Frings suffered a fractured rib in Monday's 1-0 win over Austria in Group B.
"Podolski definitely won't train today and it's going to be tight for Thursday," Loew told a news conference.
"The medical department will do everything they can to get him fit but he had real problems in the second half against Austria (on Monday)."
Frings complained of discomfort on Tuesday and a subsequent X-ray at a hospital in Lugano revealed a broken rib.
"As Frings is an important member of the team we'll exhaust every possibility to get him fit to play against Portugal," Loew said in a statement released by the German Football Association.
"He'll receive intensive treatment over the coming hours. A decision will not be made until Thursday."
Playing as a midfielder, Podolski has scored three of Germany's four goals in the tournament and with forwards Mario Gomez and Miroslav Klose in poor form his absence would be a significant blow for Loew's side.
Frings is a hard-running, aggressive presence alongside Michael Ballack in midfield and there is no like-for-like replacement in the squad.
Earlier on Tuesday, Loew said Bastian Schweinsteiger, who was suspended against Austria, would probably return on Thursday.
"He didn't start in either of the first two games but when he came on he gave us pace and creativity," said the coach. "I expect him to be back in the team on Thursday."
Loew also expressed confidence in Gomez.
"I'm sure we can still benefit from his abilities at this tournament," he said. "His finishing has been disappointing so far but he's not just standing there. He's working hard and helping the team."