"I have some exciting news to share with you," said a statement released on Federer's personal website and Facebook page. "Late last night, in Switzerland, Mirka and I became proud parents of twin girls."

Tennis' top-ranked player said the girls were named Charlene Riva and Myla Rose.

"They are both healthy and, along with their mother, they are doing great," Federer's Facebook page said. "This is the best day of our lives."

well-kept secret

They were the first children for the couple, married in April. Federer announced Mirka's pregnancy in March, but it was a well-kept secret that she was expecting twins.

More than 1,500 fans from all over the world sent congratulations to Federer's website.

"Here comes the future tennis players," said one fan.

"Wait 15 to 20 years. The Williams sisters will look like a joke compared to the Federer sisters," another said.

The birth came at an opportune time for Federer, who won the Wimbeldon title earlier this month but is not scheduled to return to the ATP tour until August 10, in Montreal.

Swiss daily Blick said Friday it is possible that Federer will extend his leave and miss the Montreal Masters.

"I want to think basically how I want to continue," he told the tabloid in an interview shortly after Wimbeldon.

Earlier this month, Mirka sat courtside through the nerve-racking Wimbledon final in which Federer beat American Andy Roddick 5-7, 7-6 (6), 7-6 (5), 3-6, 16-14 to clinch his 15th grand slam title, breaking the record held by Pete Sampras.

The 27-year-old Federer met Mirka - born Miroslava Vavrinec in Slovakia - in 2000 when they were competing for Switzerland in the Sydney Olympics.

Mirka, 31, emigrated with her family to Switzerland as a child and, after playing on the WTA Tour and retiring prematurely due to injury, she became one of Federer's managers.