Manchester City are reportedly concerned that Leroy Sane may have injured his ACL in Sunday's Community Shield.
The German midfielder went off after just 13 minutes following a collision with Liverpool defender Trent Alexander-Arnold and is currently undergoing tests to determine the full extent of the problem.
The Telegraph reports that the Premier League champions are expected to make a decision later today as to whether the former Schalke player will need surgery.
Sane has been a top target for Bayern Munich throughout the summer transfer window, with boss Niko Kovac recently expressing his 'confidence' that he would join the Bavarian giants before the German transfer window closes on September 2.
The German side, however, are believed to be reluctant to pay the £137m asking price that City have set for the 23-year-old, who still has two years left to run on his current contract.
The report suggests that Bayern will be keeping a close eye on the extent of Sane's injury, as that could affect whether they register a formal bid for the player in the next few weeks.