Elena Vesnina of Russia stunned 32nd seed Shuai Peng to reach the second round of the U.S. Open with a straight-sets win Tuesday.
Vesnina, the world No, 93, broke down strong resistance from China's Peng in the first set to win 7-6 (7-5), 6-1.
In the second round, Vesnina faces her compatriot Ekaterina Makarova, ranked 42nd in the world, who swept past Eleni Daniilidou of Greece 6-1, 6-4.
Elsewhere, 24th seed Klara Zakopalova of the Czech Republic was upset 6-4, 6-4 by her fellow Czech Andrea Hlavackova.
Hlavackova will play Kazakhstan’s Galina Voskoboeva in the second round.