BEIJING, Dec. 26 (Xinhuanet) -- Former world No. 1 and 17-time grand slam winner Roger Federer said on Tuesday that he and wife Mirka are expecting another child.

Federer became a father in July 2009 when Mirka gave birth to twin daughters, Myla Rose and Charlene Riva.

“Mirka and I are very happy to share the news that Myla & Charlene will be big sisters in 2014! Happy Holidays,” the 32-year-old announced on his website.

His agent Tony Godsick confirmed the news. Federer spent more weeks at No. 1 than anyone else in the history of the ATP rankings.