MADRID, Spain -- Roger Federer was relieved to find himself preparing for a Tennis Masters Series-Madrid semifinal against Juan Carlos Ferrero after being pushed to the limit on Friday.

Federer lost the first set to another Spaniard, unseeded Feliciano Lopez, and dug himself out of trouble while serving at 0-40 and 4-4 in the second set.

The Wimbledon champion eventually came through 4-6, 7-6 (3), 6-4 against the big-serving Lopez, who for long periods of the match appeared set to pull off a big upset in the 2.45 million euros indoor event.

"There wasn't much I could do," Federer said after a victory that took two hours, 15 minutes. "I just hung in there. I could have lost in straight sets, 6-4, 6-4, when I was down 0-40 there in the second set. I really battled hard today."

Ferrero beat Paradorn Srichaphan 6-4, 6-2 on Friday. If Ferrero had lost, No. 2 Andy Roddick would have replaced him atop the ATP Tour rankings.

Federer, of Switzerland, is trailing Ferrero and Roddick in the race for the year-end No. 1 ranking and Saturday's semifinal will be a big chance to make up some of the deficit.

"The game against Lopez was a big match but tomorrow against Ferrero is even bigger," Federer said.

"I'm playing a guy who is in contention as well. I just hope I can play well tomorrow and beat him.

"Ferrero didn't miss too much in his game today but he knows I will play aggressively."

Information from Reuters and The Associated Press was used in this report.