Serena welcomes Federer to retirement

Serena Williams welcomed Roger Federer to the tennis "retirement club" on Thursday, saying she has always admired and looked up to the Swiss legend.

Federer, a 20-time Grand Slam champion, said Thursday he would retire after playing next week in London at the Laver Cup.

Among those sending congratulations to the 41-year-old icon for his tremendous career was 23-time Grand Slam winner Williams, who said she was "evolving" away from tennis, with last week's US Open expected to be her final tournament.

"I wanted to find the perfect way to say this, as you so eloquently put this game to rest – perfectly done, just like your career," Williams said in an Instagram post.

"I have always looked up to you and admired you. Our paths were always so similar, so much the same. You inspired countless millions and millions of people – including me – and we will never forget."

Serena came as close as she has come to firmly saying her own career is complete by welcoming Federer into "the retirement club”.

"I applaud you and look forward to all that you do in the future," Williams wrote. "Welcome to the retirement club. And thank you for being you @rogerfederer."