KEY BISCAYNE, Fla. (AP) – Andy Roddick’s winning percentage against Roger Federer could be worse.

Instead of .063, it could be .000. Roddick has lost to his nemesis 15 times, including their past 11 meetings. And yes, Roddick has won only six of the 43 sets they’ve played.

But Roddick beat Federer once and expects to do it again, maybe even Thursday night. They’ll play in the quarterfinals of the Sony Ericsson Open.

“It will be good,” Roddick said, and he almost sounded convincing. “I always look forward to it, and I do believe that I’ll beat him one of these times. Hopefully that will be this time around.”

The top-ranked Federer will be a heavy favorite, however. Still seeking his first title this year, Federer looks highly motivated and has yet to lose a set in three rounds, while Roddick twice had to overcome one-set deficits.

Plus, a 15-1 record gives a fellow a slight psychological edge.

Roddick became the lone remaining American in the men’s draw when James Blake lost in the quarterfinals Wednesday to Rafael Nadal, 3-6, 6-3, 6-1. Jelena Jankovic advanced to the women’s semifinals when Elena Dementieva retired with a back injury trailing 6-3, 3-1.

The meeting between Federer and Roddick will be their first since November at the Tennis Masters Cup in China. Roddick won six games in two sets.

After one loss, Roddick joked his solution might be to punch Federer. Another time, Roddick declined to describe their matches as a rivalry because he said they were too one-sided.

His only victory came in Montreal in 2003, and he conceded the frustration of repeated failures against Federer makes it difficult to stay positive.

“If I’m being frank, it is hard,” Roddick said. “But at the same time … the good thing about tennis is you pretty much start over at the beginning of every day. Even after some of my tough losses, I think I’ve always been pretty clear that I would get up the next morning and keep going. You know, I’ve had a pretty good career doing that so far.”

Nadal showed his typical tenacity in the quarterfinals, beating Blake despite converting only four of 19 break-point chances. Ranked No. 2, Nadal is seeking his first tournament title this year and his first title at Key Biscayne.

“Right now I am feeling like I am playing at my best level,” Nadal said.

Blake said he felt fine physically in the afternoon heat and could have played three more sets, but he blamed himself for allowing Nadal back into the match.

“I played my game for a while, and then I got a little indecisive,” Blake said. “I wasn’t attacking as much. They say the heat can affect your mind, too. Maybe it got to my head.”

On Friday, Nadal will play the winner of Wednesday night’s match between 10th-seeded Tomas Berdych and No. 31 Igor Andreev.

The fourth-seeded Jankovic finds herself in the final four after barely surviving her opening match. In the third set against Sofia Arvidsson, Jankovic overcame a 5-1 deficit, then saved five match points in a tiebreaker

“It was a scary feeling, you know, just thinking that I may be over with this tournament,” Jankovic said. “But I was really strong mentally and was able to get through that match, which gave me a lot of confidence for the rest of the tournament.”

The Serb has since swept every set in the past three matches. She needed only 58 minutes against Dementieva, bothered by back trouble that first surfaced Tuesday.

Jankovic had never advanced beyond the third round in five previous appearances at Key Biscayne. She’s seeking her first tournament title this year, and on Thursday she’ll face the winner of Wednesday night’s match between No. 13 Dinara Safina and No. 19 Vera Zvonareva.

AP-ES-04-02-08 1853EDT