Former No. 1 Caroline Wozniacki is gone from the U.S. Open, falling 4-6, 6-4, 6-3 on Saturday night to Camila Giorgi, a 136th-ranked qualifier.
Giorgi hit 46 winners to 13 for Wozniacki, the 2009 runner-up at Flushing Meadows who came in seeded sixth.
Giorgi will play another Italian, No. 10 Roberta Vinci, in the fourth round. This is the Giorgi's second round-of-16 appearance in a major; she made it that far at Wimbledon last year.
The 21-year-old, who won three matches in qualifying to earn her spot in the main draw, is the first woman qualifier to reach the fourth round of the U.S. Open since Anna-Lena Groenefeld in 2008.