Roger Federer will miss the rest of the 2020 tennis season after undergoing a second knee surgery a few weeks ago, the winner of 20 grand slam singles titles said on Wednesday.

Federer struggled with injury at the 2020 Australian Open, where he made a semi-final exit to eventual champion Novak Djokovic, and has not played since.

He underwent surgery on the right knee in February, but said he needed another procedure after suffering a setback while rehabilitating after the initial operation.

“A few weeks ago, having experienced a setback during my initial rehabilitation, I had to have an additional quick arthroscopic procedure on my right knee,” the 38-year-old said in a Twitter post.

“I will be missing my fans and the tour dearly but, I will look forward to see everyone back on tour at the start of the 2021 season.”

pic.twitter.com/zXnR7gAZQA

— Roger Federer (@rogerfederer) June 10, 2020

Just how much tennis he will actually miss remains up in the air.

The ATP Tour is currently shut down until at least the end of July due to the coronavirus pandemic, with the US Open and French Open still set for a hectic back-to-back schedule in August and September.

The Swiss had knee surgery to repair a torn meniscus in 2016 and missed the second half of that season.

When he returned to the tour for the 2017 season it looked like he had never been away, winning the Australian Open to end a near five-year grand slam title drought and adding the Wimbledon title later that year.

Rest up Roger, best wishes Rod. https://t.co/TLxHGU5hfh

— Rod Laver (@rodlaver) June 10, 2020

The last of Federer’s record 20 grand slam singles titles came at the 2018 Australian Open.

The closest he has come since was at Wimbledon last year, when he lost in the final.

The ATP Tour is currently shut down until at least the end of July due to the pandemic, with the US Open and French Open still set for a hectic back-to-back schedule in August and September.