Canadian 15th seed Bianca Andreescu beat former Australian Open champion Caroline Wozniacki in the third round of the US Open.
The 19-year-old, playing at Flushing Meadows for the first time, won 6-4 6-4 in a match featuring 10 service breaks.
Denmark's Wozniacki, 29, is a two-time US Open finalist.
Andreescu, who has won titles in Toronto and Indian Wells this year, will face American Taylor Townsend in the next round.
World number 116 Townsend knocked out Wimbledon champion Simona Halep in the second round and beat Romanian Sorana Cirstea 7-5 6-2 on Saturday.