Federer's wife Mirka and their twin daughters, file photo.

MADRID - Roger Federer withdrew from the Madrid Open on Tuesday to welcome the birth of his second set of twins.

Federer said on his webpage early Tuesday he was pulling out of the tournament "to be with my wife Mirka during these next few exciting weeks for our family." The fourth-ranked Swiss player, who already has twins, said he would "rejoin the tour soon."

Later, Federer tweeted: "Mirka and I are so incredibly happy to share that Leo and Lenny were born this evening! (hash)TwinsAgain (hash)Miracle"

Federer's agent, Tony Godsick, confirmed to The Associated Press that the baby boys were born in Zurich, Switzerland, on Tuesday. Federer and his wife Mirka are already parents to twin daughters.

Federer had said last month he was prepared to skip tournaments to be with his wife when she gave birth.

The 32-year-old Federer did not specify if he would return for the Rome Masters next week, but Godsick said the 17-time Grand Slam champion intended to enter the French Open, which begins May 25.

"Roger has plans to play the French Open, and he'll take it step-by-step as to what he plays before that," Godsick said in a telephone interview.

Federer, a three-time winner in Madrid, hasn't missed a Grand Slam tournament since 2000.

Federer's 28-5 record on the season is the ATP's best, with the former No 1 having won a title in Dubai.

Polish player Lukasz Kubot took Federer's place in the Madrid draw, and will face Gilles Simon of France in a second-round match.

Second-ranked Novak Djokovic also withdrew from Madrid because of a long-term wrist injury.