updated 2:25 a.m. ET Aug. 30, 2008

NEW YORK - Roger Federer flicked a final winner, trotted to the net and started to shake hands. Then, there was one last challenge.

Playfully, Thiago Alves called for a replay review.

So the man trying for his fifth straight U.S. Open title and an overmatched qualifier shared a laugh, watching together as the giant scoreboards above Arthur Ashe Stadium confirmed the call: The ball landed squarely on the line, and Federer had won 6-3, 7-5, 6-4 on Friday.

Federer swept a guy ranked 137th, someone who spent this year in the minors and was playing his first tour-level event of the season. Still, it was hardly a breeze.

“The depth in men’s tennis is immense,” Federer said.

In the night matches delayed more than an hour by rain, former Open champion Marat Safin lost to No. 15 Tommy Robredo, 4-6, 7-6 (4), 6-4, 6-0.

Eighth-seeded Andy Roddick, who won the 2003 Open, overcame a big early deficit to beat Ernests Gulbis 3-6, 7-5, 6-2, 7-5 in a match that ended after 1:30 a.m. Saturday. Roddick was down a set and trailed 5-3 in the second when he reeled off seven consecutive games to take control against his unseeded opponent.

Federer is down to his last chance to win a Grand Slam this year, part of a tough season that saw him lose his No. 1 ranking to Rafael Nadal.

Though they well could meet in this final, Federer has not tracked his nemesis through the tournament and didn’t watch Nadal wrap up his match Thursday night in straight sets.

“I schedule my life around my life, not his,” Federer said, smiling. “I was expecting five sets. I was there for four and five, but he wasn’t there anymore.”

To Alves, Federer remains on top.

“He is the biggest player for sure. Nadal is playing good tennis this year, but for me Federer is the best one,” he said.

And did Federer seem vulnerable?

“No. I didn’t feel that,” Alves said.

Never a huge fan of replay, Federer hardly minded when Alves made that last challenge.

“I don’t think it’s affected a whole lot of matches. I don’t know how many times it’s saved a match, because that’s what it’s there for really. But at the big tournaments at the big courts, usually you have the best linespeople as well,” Federer said.

“The worst linespeople are usually on the outside courts where you need it more. That’s the problem with the system,” he said.

In other men's matches, third-seeded Novak Djokovic beat Robert Kendrick 7-6 (8), 6-4, 6-4 and fifth-seeded Nikolay Davydenko beat Agustin Calleri 6-4, 6-4, 7-6 (2).

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