Former World No. 3 Marin Cilic withdrew from Wimbledon on Wednesday due to the right knee injury he sustained earlier this year.
Cilic, 34, injured the knee in January in India. He defeated Roberto Carballes Baena of Spain and then had to pull out of his next match due to the knee pain.
Cilic of Croatia lost in the 2017 Wimbledon final to Roger Federer in three sets.
"I'm sad to be missing the grass season and especially Wimbledon; this is a highlight of the season for every tennis player, but I know how important it is not to rush the recovery process," Cilic wrote on Instagram. "Things have generally been going well the last few weeks with my post-surgery training so I'm staying positive and focused on my long-term recovery.
"I hope that I'll be competing very soon. I miss being on Tour, the tournaments and the fans, and I can't wait to get back to all of that, to feel the thrill of stepping on court & competing. Until then, I'll keep training and sharpening my motivation."
Cilic does have one Grand Slam title -- he beat Japan's Kei Nishikori in three sets in the 2014 U.S. Open.
Wimbledon starts Monday in London.
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