Peng Shuai of China upset fourth-seeded Agnieszka Radwanska of Poland 6-3, 6-4 in a shocking start to the women's second round of the U.S. Open on Wednesday.
The 28-year-old Peng, the doubles World No 1, used her piercing, two-fisted groundstrokes to put Radwanska on the defensive and claimed the biggest scalp of the championship on her third match point with a backhand crosscourt winner.
Peng, the French Open doubles champion who is looking for her first career WTA Tour title, registered 28 winners in the 96-minute match.
The unseeded Chinese, ranked 39th in singles, will play either 28th seed Roberta Vinci of Italy or Irina-Camelia Begu of Romania in the third round of the year's final Grand Slam.
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