Petra Kvitova's US Open preparations were dealt a blow as Timea Babos upstaged Kristina Mladenovic and Eugenie Bouchard advanced to the last 16 in New Haven.
With the year's final grand slam set to get underway at Flushing Meadows next week, third seed Kvitova suffered a shock defeat to Shuai Zhang at the Connecticut Open on Monday.
There was another high-profile casualty at the WTA Premier event as fourth seed Mladenovic was bundled out by
Former world number seven Bouchard, meanwhile, trounced Lauren Davis on the day of the first solar eclipse since 1918.
KVITOVA SWEPT ASIDE BY WORLD NO. 29
A three-time champion in New Haven, Kvitova lost 6-2 6-1 to Zhang.
Kvitova has struggled on the hardcourt swing, suffering early exits in Cincinnati and Toronto.
And it did not get any better for the two-time grand slam winner after she was eliminated in just 67 minutes against Zhang, who has not featured in New Haven since 2013.
BABOS PUNISHES WASTEFUL MLADENOVIC
The unseeded Hungarian claimed her first top-20 victory of the season after accounting for Mladenovic 7-5 7-5.
Mladenovic doubled-faulted seven times in the opening set as Babos moved ahead.
The Frenchman responded in the second, erasing a 2-0 deficit to have the chance to serve out the set at 5-3 but she double-faulted again, finishing with 12 in total.
Mladenovic had another set point on Babos' serve, which she failed to convert and the latter pounced to progress.
Through to the round of 16 for the first time in her career, Babos will take on Daria Gavrilova, who outlasted Kristyna Pliskova 7-5 4-6 7-5.
BOUCHARD WINS ON HISTORIC DAY
It was a once-in-a-lifetime moment as a total solar eclipse gripped the United States.
Canadian star Bouchard enjoyed the phenomenon after making light work of home favourite Davis 6-1 6-3.
"It's so cool. I was kind of upset that I was playing exactly during it but at the same time I was like this is such a unique moment," she said. "I was able to win a match during an eclipse. This is the only time in my career this will happen.
"Right before I went on the court after my warm-up, they were waiting for me to walk on and I walked by someone with the glasses who was looking up and I was like 'hey give me those, I need to see this, it's a once in a lifetime opportunity'."
Bouchard will meet defending champion Agnieszka Radwanska in the round of 16.
Thank you adorable fan who gave me these eclipse glasses after my match & who insisted I still use them even tho the eclipse was over pic.twitter.com/pNPiJcjoIi-- Genie Bouchard (@geniebouchard) August 21, 2017