Bastian Schweinsteiger is a major doubt for Germany's matches against England and Italy after picking up a knee injury in training.
The Germany captain has only recently returned to the pitch after spending two months out for Manchester United between January and March with a knee problem picked up against Sheffield United in the FA Cup.
Head coach Joachim Low had stressed his confidence that the worst of Schweinsteiger's fitness woes were behind him, but the 31-year-old suffered an issue at the end of training on Tuesday.
Schweinsteiger left the Germany camp on Wednesday to go for an MRI scan with specialist Dr Hans-Wilhelm Muller-Wohlfahrt in Munich, where the level of damage will be assessed.
Arsenal playmaker Mesut Ozil also sat out Wednesday's session to rest a knock to his ankle sustained against Everton on Saturday, while Karim Bellarabi did the same due to a bruised foot.
World champions Germany play England on Saturday in Berlin, before they host Italy in Munich next Tuesday.