Tennis' top-ranked player became a father for the first time when his wife, Mirka, gave birth to twin girls Thursday.
"I have some exciting news to share with you," Federer said on his Web site and Facebook page. "Late last night, in Switzerland, Mirka and I became proud parents of twin girls."
They are named Charlene Riva and Myla Rose, and Federer said the girls and his 31-year-old wife are "doing great."
"This is the best day of our lives," he said on his Facebook page.
The 27-year-old tennis great married Mirka in April. He announced her pregnancy in March, but it was a well-kept secret that she was expecting twins.
More than 1,500 fans worlwide sent congratulations to Federer's Web site.
"Here comes the future tennis players," said one fan.
"Wait 15 to 20 years," another said. "The Williams sisters will look like a joke compared to the Federer sisters."
Federer is not scheduled to return to the tour until Aug. 10 in Montreal. Mirka sat courtside this month when Federer won an epic, five-set Wimbledon final against Andy Roddick for his 15th Grand Slam title, breaking Pete Sampras' record.
Federer met Mirka - born Miroslava Vavrinec in Slovakia - in 2000 when they were competing for Switzerland in the Sydney Olympics. Mirka emigrated with her family to Switzerland as a child. After playing on the WTA Tour and retiring because of injury she became one of Federer's managers.