World No.1 Jannik Sinner has withdrawn from the Cincinnati masters due to a knee injury. Sinner hasn’t played since Wimbledon, where he defeated Alexander Zverev in the final to defend his title. The withdrawal from Cincinnati is a big setback to his preparations for the US Open, having also withdrawn from the Canadian Open. Sinner will thus enter the US Open without any hard court matches following Wimbledon.

The Cincinnati Open’s main draw kicks off on August 13, ahead of the U.S. Open starting August 30.

Sinner said he took the decision after consulting his doctors, saying he is not ready to compete, adding that getting fit before the US Open remains his priority.

“After consulting with my doctors and my team, I have to announce that I need to withdraw from the Masters 1000 tournament in Cincinnati. My right knee has been bothering me, and despite our best efforts, I’m not ready to compete yet. I’m focused on preparing for the U.S. Open now,” Sinner said in a statement.

Fitness concerns have hampered Sinner in recent times. He was knocked out of the French Open in the second round after fatigue, dizziness, and low energy on the court. He also wasn’t at peak fitness during the semifinal defeat to Novak Djokovic at the Australian Open.

“We know Carlos is doing everything he can to get back to playing tournaments as soon as possible,” tournament director Bob Moran said in a statement. “We wish him the best with his recovery and look forward to welcoming him back to Cincinnati in the future.”