BEIJING - Roger Federer will miss the rest of the 2020 season after having a further operation on his right knee, the 20-time Grand Slam winner announced on Wednesday.

The 38-year-old Swiss had the initial arthroscopic surgery in February but said he suffered a setback with his rehabilitation.

"I will look forward to seeing everyone back on Tour at the start of the 2021 season," Federer said on Twitter.

"Now, much like I did leading up to the 2017 season, I plan to take the necessary time to be 100 percent ready to play at my highest level."

In 2016, Federer missed the majority of the season with a knee injury, but returned the following year to win the Australian Open and Wimbledon.

Federer has not played since losing to Novak Djokovic in the Australian Open semifinals in January.

The ATP Tour is currently suspended until at least the end of July because of the COVID-19 pandemic, with the US Open currently scheduled to start on August 31 and the French Open beginning on September 20.