Roger Federer withdraws from Madrid Open with back injury

Roger Federer has pulled out of this week's Madrid Open due to a back injury.

The third-ranked Federer announced his withdrawal on Monday after the Swiss suffered the injury during practice Saturday.

Federer said he is withdrawing as a precaution.

The 35-year-old Federer, a three-time winner in Madrid, described the injury as "normal back things I've had in past. I'm OK with it. At least I know what it is."

Federer had added the tournament to his schedule as part of his preparations for the French Open in three weeks.

"I'd rather play it safe and get ready for Rome," the 17-times grand slam champion said. "If I can't play Rome, it's not the end of the world, but hopefully I'll get to play."

Novak Djokovic, Rafael Nadal, defending champion Andy Murray and Stan Wawrinka remain in the men's draw.

On Friday, Serena Williams announced that she would not play in the Madrid tournament due to flu-like symptoms. Williams is a two-time winner of the event (2012, 2013).