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, Federer had won 6-3, 7-5, 6-4 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.
On the women's side, it's shaping up as even more of a scramble.
A day after No. 1 Ana Ivanovic lost to 188th-ranked Julie Coin, third-seeded Svetlana Kutznetsova became the latest upset victim when Katarina Srebotnik beat her 6-3, 6-7 (1), 6-3.
"It can happen with everyone," said Olympic champion Elena Dementieva, who moved into the fourth round.
Novak Djokovic, Jelena Jankovic and Nikolay Davydenko also won during the day.
In night matches delayed more than an hour by rain, No. 12 Marion Bartoli defeated No. 23 Lindsay Davenport 6-1, 7-6 (3), and No. 15 Patty Schnyder beat Magdalena Rybarikova 7-6 (4), 6-4. Also, former Open champion Marat Safin lost to No. 15 Tommy Robredo, 4-6, 7-6 (4), 6-4, 6-0.
Eighth-seeded Andy Roddick defeated Ernests Gulbis in four sets in a late match.
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.
Kuznetsova, who won the Open in 2004 and finished second last year, had trouble fending off Srebotnik's frequent charges to the net.
Srebotnik fell to her knees a split-second before Kuznetsova's last shot sailed over the baseline. After beating Serena Williams in the French Open this year, the 28th-ranked Slovenian had another reason to celebrate, having gone farther than ever before at Flushing Meadows.
Second-seeded Jankovic won another sneaker squeaker, playing 28 points in the last game to finish off Zheng Jie 7-5, 7-5.
Jankovic came out full of energy, showing no ill effects of a bad left leg that cramped after she played Wednesday. She bounded back and forth and, in her trademark style, often came to screeching stops while doing the splits to reach shots.
"As long as I'm doing the splits, that means I'm healthy," she said. "When I'm not doing the splits, you know there's something wrong."
"I'm not too sure about my body if I go into a split, who knows if I'll come back up?" she said.
Still waiting for that elusive big win, Jankovic is trying to reach her first Grand Slam final. She needs three more wins with Justine Henin retired, Maria Sharapova hurt, Ivanovic out and the Williams sisters in the opposite bracket, this figures to be her best chance.
Jankovic needed more than two hours to beat the 37th-ranked Zheng after playing for nearly three hours in the second round.
"I wish I didn't have any drama in my matches. I wish I would win nice and in a simple way," she said. "Who likes drama? Do you know anybody that likes to get involved into tight matches?"
Jankovic is one of six women who still have a chance to be ranked No. 1 after the Open, with Ivanovic among them despite her loss.
Third-seeded Djokovic beat Robert Kendrick 7-6 (8), 6-4, 6-4 and fifth-seeded Davydenko beat Agustin Calleri 6-4, 6-4, 7-6 (2). Fifth-seeded Dementieva beat Anne Keothavong 6-3, 6-4.