NEW YORK Even for the mathematics major from Clemson, it just didn't add up: How could someone who recently struggled so badly she wanted to quit tennis stay on the court with the No. 1 player in the world?
Ana Ivanovic probably wondered the same thing.
In one of the biggest upsets in the sport's history, the top-seeded Ivanovic was ousted from the U.S. Open, stunned by 188th-ranked Julie Coin 6-3, 4-6, 6-3 in the second round Thursday.
"Obviously, if you would ask me at the moment if I'm playing like a No. 1, probably not," Ivanovic said. "It's very frustrating because I know I can play so much better."
Never before in the Open era that began in 1968 had the No. 1 woman lost this early in the tournament. Plus, all the favorites had been breezing at Flushing Meadows.
The French Open champion seemed to be rallying in the third set when Coin suddenly recovered to win 10 straight points. The 25-year-old French math whiz screamed when Ivanovic's last shot sailed out, then hopped for joy and hit an extra ball high into the stands.
"I don't know how I'm going to sleep tonight," said Coin, who's earned less than $100,000 in her pro career. "I don't know when I will realize everything."
Even after Ivanovic struggled in the first round with an injured right thumb that limited her practice time, there was no way to see this coming.
Coin spent much of the year playing in minor league events and nearly got knocked out of the qualifying event to merely make it into the Open. She recently played so poorly she thought about giving up the sport and relying on her degree.
"I was thinking, 'Am I really made to play tennis?"' she said.
Ivanovic quickly gathered her gear and left the court, her hopes of another Grand Slam championship dashed. She smiled after the match, simply happy to be pain-free, and did not appear upset by the upset.
"I think what I experienced so far is girls, when they play against higher-ranked players, they have nothing to lose, so they go for their shots," she said. "Many times they play matches of their life. Not only in women's tennis, also in men's."
Still, Coin couldn't have figured on it. Asked whether she'd thought such a win was possible, she gave a direct, honest answer.
"No," she said.
And when did she believe it might happen?
"I guess when it was over," she told the crowd at Arthur Ashe Stadium, drawing a huge ovation.
If there was any suspicion that Coin was wavering, she steadied herself by rallying in the third set. It was Ivanovic who looked jittery, hitting shots directly into the net or way out.
Top-seeded Rafael Nadal hoped to avoid a similar fate Thursday night.
Venus Williams and sister Serena won earlier in the day. James Blake, David Ferrer, Andy Murray and Dinara Safina joined them in moving into the third round.
The Ivanovic-Coin match was originally scheduled for the smaller Louis Armstrong Stadium, but was moved to the main Ashe stage to give the crowd a treat. The fans hardly knew what really was in store.
Tentative at times, Ivanovic seemed to regain her edge midway through third set. She led 40-0 in the fifth game and was about to break Coin's serve when suddenly the momentum shifted.
Coin came back to hold, starting her decisive streak.
Ivanovic tried to stave off Coin in the final game, but it was too late for the 20-year-old Serbian star. Coin won on her third match point quite a result for someone playing in her first tour-level event.
Coin had tried to qualify for the Australian Open, French Open and Wimbledon and never made any of them. And she certainly wasn't anything bankable going into this match she'd earned less than $100,000 lifetime as a pro, and was facing someone who'd won nearly $6 million.
Next up for Coin in the third round is No. 32 Amelie Mauresmo, who beat Kaia Kanepi 2-6, 6-4, 6-0. Coin and Mauresmo once played at the same club near Paris and shared the same coach, yet thoughthey don't know each other well.
"I know she was No. 1," Coin said.
Going into this Open, Ivanovic had played only two matches since Wimbledon while her thumb healed. The injury forced her to withdraw from the Olympics before they began, limited her practice time and sent her from Beijing to Australia for treatment.
Fourth-seeded Serena Williams routed Elena Vesnina 6-1, 6-1 and seventh-seeded Venus Williams overwhelmed Rossana de Los Rios 6-0, 6-3 in only 59 minutes.
"I'm very satisfied so far, the way it's gone," Williams said.
Venus Williams breezed past an opponent ranked 117th. After teaming with her sister to win Olympic gold in doubles, she stayed on course to play Serena in the quarterfinals here.
"Whichever way the draw goes, whichever way the matches go, as long as hopefully it's a win for me, I'm pretty happy about it," she said.
Williams is the last woman to win consecutive championships at the U.S. Open, but hasn't taken the title since 2001.
"Oh yes, I remember. I won't forget, but I'd like to have a more recent memory as of, like, '08," she said. "Kind of overdue."
Blake advanced when Steve Darcis pulled out because of a bad lower back. Seeded ninth and coming off a tough, five-set match in the first round, Blake lost the first set 4-6, then won 6-3 and was ahead 1-0 when Darcis retired.