Berlin - Germany's Sabine Lisicki confirmed on Monday she expects to miss the rest of the 2015 season as she continues to struggle with a knee injury.
"We have tried everything, but my knee isn't ready," the 2013 Wimbledon finalist wrote on her Facebook page.
"The current state of play is that I won't play any more tournaments this season."
Lisicki had complained of pain in her knee during the early rounds of the US Open earlier this month before her last-16 exit to Romania's Simona Halep.
She has been treated by famous Munich-based doctor Hans-Wilhelm Mueller-Wohlfahrt, who looks after the German football team and athletics stars, including Usain Bolt.
"The doctors, my team and I have all worked hard to get me back fit as soon as possible and I will be back by the start of the new season at the latest," she added.
It has been a disappointing season for the German who reached the semi-finals of Indian Wells in March and also made the last four at the Birmingham tournament in June.
She went out of the Australian Open in the first round and reached the third round of Roland Garros and Wimbledon, which has left her 28th in the world rankings from a high of 12th in May 2012.