Camila Giorgi sprang an upset to defeat four-time champion Caroline Wozniacki 6-4, 6-2 on Wednesday and reach the quarter-finals of the WTA Connecticut Open, a final warm-up for the US Open.
The Italian saw off the former world number one in 78 minutes to book a last-eight date with Spain's Garbine Muguruza, who eliminated Chinese qualifier Peng Shuai 6-2, 3-6, 6-3 in another second-round match.
The unseeded Giorgi also ousted Wozniacki in last year's US Open, but lost their only other meeting this year at Eastbourne.
Wozniacki, whose best Grand Slam showing was a 2009 US Open runner-up effort, won the title at New Haven from 2008 to 2011, but saw her record at the Yale University event dip to 24-3.
The 24-year-old Dane's only prior losses since Wimbledon came in three-set battles with world number one Serena Williams in Montreal and Cincinnati.
"I knew I was going to get limited break chances and when I did get them, I didn't convert," Wozniacki said. "I knew I had to be aggressive out there and try to push her back, but I didn't manage to do that. She played well and I didn't."
The defeat does allow Wozniacki a few extra days to prepare for the year's final Grand Slam, which starts on Monday.
{{/usCountry}}The defeat does allow Wozniacki a few extra days to prepare for the year's final Grand Slam, which starts on Monday.
{{/usCountry}}"I would have loved to have been here longer, but it wasn't to be this year," Wozniacki said. "Now I just need to take the positives out of it. I get a few extra days to rest up and practice for the US Open."
Wimbledon finalist Eugenie Bouchard also failed to make it to the quarter-finals.
Australian veteran Samantha Stosur briskly ousted the third-seeded Canadian 6-2, 6-2.
Stosur next faces Belgian Kirsten Flipkens, who beat Germany's Andrea Petkovic 4-6, 7-6 (7/4), 7-6 (8/6).
Thursday's other two quarter-finals were already set. Slovakian Magdalena Rybarikova, who ousted top-seeded Simona Halep, will take on American Alison Riske, and second-seeded Wimbledon champion Petra Kvitova will face fellow Czech Barbora Zahlavova Strycova.