(REUTERS) – Roger Federer has said he will miss a number of tournaments, including the French Open, after undergoing keyhole surgery on his knee in Switzerland on Wednesday but he is targetting a return in time for Wimbledon.The 20-time Grand Slam champion struggled with injury at the Australian Open, where he lost in the semi-finals to eventual champion Novak Djokovic, and has not played since.Federer, 38, said he would miss ATP tournaments in Dubai, Indian Wells, Bogota and Miami as well as the French Open which starts at the end of May.It will be the fourth time in five years that Federer, champion at Roland Garros for the only time in 2009, has missed the claycourt slam.“My right knee has been bothering me for a little while. I hoped it would go away, but after an examination and discussion with my team, I decided to have arthroscopic surgery in Switzerland yesterday,” Federer said in a statement on Twitter here.“After the procedure, the doctors confirmed that it was the right thing to have done and are very confident of a full recovery.”The Swiss skipped the entire claycourt season in 2017 and 2018 and last year played only two tournaments on the surface before arriving in Paris for the French Open where he lost to Rafael Nadal in the semi-finals. His agent told Reuters last week that Federer was planning on playing only at Roland Garros while skipping the Madrid and Rome Masters. The French Open begins on May 24.While the prospect of Federer being away from the Tour for so long will dismay his vast army of fans, they can be encouraged that his decision to undergo knee surgery for a second time seems designed to extend his career. “I can’t wait to be back playing again soon, see you on the grass,” Federer added on his Twitter page.Federer has proved in the past that he can return to his peak after an injury layoff.He had knee surgery to repair a torn meniscus in 2016 and missed the second half of that season as he struggled to recover. But he returned in style to win the 2017 Australian Open, ending a near five-year Grand Slam title drought.Federer’s ranking will drop from its current three but he is still likely to be seeded in the top 10 at Wimbledon where he will be seeking a record-extending ninth title.