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American 17-year-old qualifier Victoria Duval scored a monumental upset on Tuesday by beating 2011 champion and No. 11 seed Samantha Stosur in the first round of the U.S. Open Tuesday.

Duval, who was playing in only her second grand slam match, posted a 5-7, 6-4, 6-4 win, which was only completed on her fourth match point. Stosur committed 56 unforced errors and had 10 double faults. A forehand winner sent Duval into the air in jubilation before the celebratory crowd at Louis Armstrong Stadium.

"The crowd helped me a lot today. I know Sam is a great champion and I watched her when she won the U.S.Open," said Duval, who won her first match against a top-20 opponent. "I know she didn't play her best today."

The story of Duval's rise to professional tennis is an eye-opening one. Although she was born in Miami, Duval spent her childhood in Haiti until the age of eight before moving back to the U.S. She started playing tennis a year before her move.

Duval's parents are Haitian. Her father, who is a doctor in Port-au-Prince; was hurt in the devastating earthquake of 2010. Her mother was a professional ballet, jazz and tap dancer.

Last year at this time, Duval was the recipient of the Maureen Connolly "Outstanding Player" award at the USTA Girls' 18s National Championships.

She will take on Slovakian Daniela Hantuchova in the second round. Hantuchova beat American wild card Maria Sanchez, 7-5, 6-2.

"There's a lot to be thankful for. You never know what could happen any day," Duval said. "Take everything I learned today and hopefully I can play like this again."

Fourth seed Sara Errani, former world No. 1 Caroline Wozniacki and 2011 Wimbledon champion Petra Kvitova were among the opening-round winners Tuesday.

Second seed Victoria Azarenka was set to play Germany's Dinah Pfizenmaier in the final night match at Arthur Ashe Stadium. The former world No. 1 Azarenka is the reigning Australian Open champ and was last year's U.S. Open runner-up to the great Serena Williams.

The former French Open runner-up Errani, of Italy, double-bageled helpless Aussie Olivia Rogowska, 6-0, 6-0, while the sixth-seeded Dane and 2009 U.S. Open runner-up Wozniacki topped Chinese Duan Ying-Ying, 6-2, 7-5, and the seventh-seeded Czech slugger Kvitova got past Japanese fellow left-hander Misaki Doi in three sets, 6-2, 3-6, 6-1, in 1 hour, 55 minutes on a warm, breezy Day 2 at the USTA Billie Jean King National Tennis Center.

"In the first round of Grand Slams it's difficult all the time so you have to be focused," said Kvitova, who was a runner-up in New Haven, Conn., last week. "I didn't play my game all the match. I didn't have focus. I have to have more confidence."

Kvitova, who captured Wimbledon in 2011, has never made it past the fourth round in New York. Her second-round opponent on Thursday will be capable Serb Bojana Jovanovski.

Meanwhile, 10th-seeded Italian Roberta Vinci, a U.S. Open quarterfinalist a year ago, handled Hungarian Timea Babos, 6-4, 6-2, 13th-seeded former world No. 1 and former French Open champ Ana Ivanovic, also a 2012 quarterfinalist in Flushing, pasted Georgian Anna Tatishvili, 6-2, 6-0, and 14th-seeded Russian Maria Kirilenko mauled Belgian Yanina Wickmayer, 6-1, 6-1.

In other action involving seeds, Ukrainian Elina Svitolina drove out No. 17 Slovak Dominika Cibulkova, 6-4, 6-3; Israeli Julia Glushko doused No. 20 Russian Nadia Petrova 6-3, 6-4; and No. 21 seed Simona Halep of Romania upended Great Britain's Heather Watson, 4-6, 6-4, 6-2. Halep is fresh off her title in New Haven and has won four events over the past two months.

No. 22 Russian Elena Vesnina drilled German Annika Beck 6-1, 6-1; No. 26 Alize Cornet, of France, downed Portuguese Maria Joao Koehler 6-3, 6-2; No. 27 Svetlana Kuznetsova of Russia beat American Mallory Burdette, 6-3, 7-5; 28th seed Mona Barthel of Germany topped Swede Johanna Larsson, 6-1, 6-4; and Taipei's Su-Wei Hsieh knocked out No. 31 Czech Klara Zakopalova 6-3, 6-3. The one-time world No. 3 Petrova has dropped her last six matches on tour.

Kuznetsova was the 2004 U.S. Open champion and 2007 runner-up.

In other matches involving Americans, Christina McHale defeated German Julia Goerges, 6-4, 6-3; 18-year-old Sachia Vickery made her WTA debut by topping Croat Mirjana Lucic-Baroni, 6-4, 6-4; Italian Karin Knapp drilled Grace Min, 6-3, 6-1; Romanian Alexandra Dulgheru took out Varvara Lepchenko, 6-7 (5-7), 6-2, 7-6 (7-5); Alison Riske ousted Bulgarian Tsvetana Pironkova, 6-3, 6-3; and Flavia Pennetta crushed Nicole Gibbs, 6-0, 6-2. Pennetta will tangle with her fellow Italian Errani on Thursday.