World No.2 Alexander Zverev has withdrawn from the U.S. Open as he continues his recovery from torn ankle ligaments, tournament organizers announced on Monday.

Zverev, 25, has not played since the injury he suffered during his semifinal against Rafael Nadal at the French Open in June. He left the court at Roland Garros in a wheelchair and subsequently underwent surgery to repair three torn ligaments in his right ankle. 

The German lost the 2020 U.S. Open final to Dominic Thiem, having led by two sets, and reached the semifinals last year. 

He is still waiting for a maiden Grand Slam title, despite winning five Masters trophies and the ATP Finals twice.

His place in the main draw of the August 29-September 11 tournament will be taken by American Stefan Kozlov. 

Zverev has been named in Germany's team for the group stage of the Davis Cup finals next month.

He may not be the only top 10 men's player absent from the year's final Grand Slam.

Novak Djokovic is also unlikely to be able to play because his refusal to take the COVID-19 vaccination does not allow him to enter the U.S. The 21-time major winner was forced out of last week's Cincinnati Masters and Montreal in Canada earlier this month for the same reason.