The 35-year-old tennis star announced earlier this week that he will not be competing in the 2017 French Open.
Roger Federer has traded tennis practice for Pippa Middleton's wedding.
The 35-year-old tennis champ, who announced earlier this week that he will not be competing in the 2017 French Open, attended Middleton's wedding to James Matthews with his wife, Mirka, on Saturday.
WATCH: Pippa Middleton Marries James Matthews: See Her Stunning Dress!
A source tells ET that the crowd cheered for Federer as he walked up the path to St. Mark's Church in Englefield, England, with Mirka, who wore a gold sparkling dress.
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Other celebrity guests included ITV news anchor Tom Bradby and his jewelry designer wife, Claudia, as well as former Byker Grove star -- and James Middleton's girlfriend -- Donna Air, who wore a long, flowing pale yellow dress and matching pillbox hat.
This year will be the first year since Federer turned pro in 1998 that he will not play a tour event on clay. The tennis star, who has 18 Grand Slam titles, said he will instead focus on grass-court and hardcourt events coming up, like Wimbledon and the United States Open.
See more on Middleton's big day in the video below.
Reporting by Jennifer Peros.
