INDIAN WELLS - Victoria Azarenka's fighting spirit just wasn't enough on Friday as the injured third seed was sent packing from Indian Wells by 66th-ranked American Lauren Davis.
With the world number four from Belarus hobbled by a painful left foot, the 20-year-old Davis triumphed 6-0, 7-6 (7/2).
"Basically all I had was my fighting spirit today," said Azarenka, who was playing her first tournament since a quarter-final exit at the Australian Open.
She had returned to the practice court less than a week earlier, after three weeks in a protective boot.
"I wanted to give my best shot," Azarenka said. "Obviously it was maybe a little bit too early. But I gave a fight. I'm pretty proud of whatever I did today.
"You also have to give her credit," Azarenka said of Davis. "In this situation it's not easy to close the match and she's done it."
Davis notched her first win against a top-10 player. She booked a third-round meeting with compatriot Varvara Lepchenko, who upset 29th-seeded Daniela Hantuchova, the 2002 and 2007 champion, 6-3, 6-2 in 84 minutes.
Second-seeded Agnieszka Radwanska reached the third round of the combined WTA and ATP Masters hard court tournament with a straight-sets win over British qualifier Heather Watson.
Poland's Radwanska, ranked number three in the world, needed one hour and 24 minutes to get past the 134th-ranked Watson 6-4, 6-3. She next faces either Russian Elena Vesnina or Germany's Annika Beck.
"The first match is always challenging," said Radwanska, who like all 32 men's and women's seeds in the $12 million tournament enjoyed a first-round bye.
In a match littered with 12 service breaks -- including seven in the second set -- she held serve to finish out the match, giving herself another reason to celebrate a day after her 25th birthday.
"I'm just happy I got through and finally won my serve the last game," she said.
Radwanska next faces Germany's Annika Beck, who beat 30th-seeded Russian Elena Vesnina 6-2, 3-6, 6-3.
Women's top seed Li Na, the Australian Open champion from China, will open her campaign against compatriot Zheng Jie on a blockbuster Saturday that will also see defending women's champion Maria Sharapova, seeded fourth, take on Germany's Julia Goerges.
Men's top seed and defending champion Rafael Nadal, third-seeded Australian Open champion Stanislas Wawrinka, fifth-seeded Andy Murray and seventh-seeded Roger Federer will also battle for third-round places.
Nadal faces Czech veteran Radek Stepanek, Wawrinka faces a tough second-round opener against big-serving Croatian Ivo Karlovic, Murray tackles Czech Lukas Rosol and Federer faces French qualifier Paul-Henri Mathieu.
Elsewhere on Friday, seventh-seeded Jelena Jankovic of Serbia, ninth seed Sara Errani of Italy and 10th-seeded Dane Caroline Wozniacki also moved into the third round.
Jankovic, the 2010 Indian Wells champion, defeated Austrian Yvonne Meusburger 6-3, 6-1.
Errani needed just 71 minutes to complete a 6-1, 6-1 victory over qualifier Sharon Fichman, while Wozniacki, the 2011 champion, beat Serbia's Bojana Jovanovski 6-1, 6-3.
In men's first-round matches, Romanian Victor Hanescu lined up a clash with second-seeded Novak Djokovic with a 7-5, 3-6, 6-4 victory over French qualifier Stephane Robert.
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