Leroy Sane is facing a prolonged spell on the sidelines after suffering anterior cruciate ligament damage.
The Manchester City and Germany winger could be out for several months after suffering the ACL injury in his side's Community Shield clash with Liverpool at Wembley.
Reports from Germany have suggested Sane, a target for Bayern Munich, has suffered a partial ACL tear which will require surgery and keep him out of action for a significant chunk of the new season.
Sane suffered the injury in what looked an innocuous challenge with Liverpool full-back Trent Alexander-Arnold, just 12 minutes into the season curtain-raiser, which ended in a 1-1 draw, with City winning on penalties.
Although Sane was forced off, City boss Pep Guardiola suggested post-match that the injury was not as serious as first feared, although subsequent tests are understood to have painted a bleaker picture.
Guardiola is expected to give an update on Sane's condition at his pre-match media conference on Friday, ahead of City's Premier League opener at West Ham on Saturday lunchtime.
If Sane is ruled out long-term, it will end Bayern's hopes of signing him, although City, who have insisted all summer they do not want to lose him, remain in negotiations with the 23-year-old about a new deal.
Sane, signed from Schalke for £37million in 2016, has two years left on his contract, with City hoping to tie him down to a new deal, having put a £145m valuation on him to keep Bayern at bay.
