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," she 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.