The German Football Association (DFB) confirmed on Wednesday that the Arsenal midfielder is struggling with the problem, meaning that he could miss Saturday's clash with Poland in Warsaw and the meeting with Ireland in Gelsenkirchen the following Tuesday.
Meanwhile, Chelsea forward Andre Schurrle went through an individual training session at the team hotel, although the DFB made no mention of a specific injury issue for the former Bayer Leverkusen man.
A tweet from the DFB read: "Training is without @Andre_Schuerrle (individual session at hotel) and @MesutOzil1088 (arrived with knee problems, having an MRI in Munich)."
Julian Draxler has also been missing from Germany's training in the last two days as he looks to shake off a cold.
Germany head Group D of qualifying following a 2-1 win over Scotland in their opening encounter against Scotland last month.
