Former champion Naomi Osaka powered past Estonia's Anette Kontaveit to reach the US Open quarter-finals.
Japan's Osaka - winner in 2018 - failed to convert five match points before sealing a 6-3 6-4 victory in New York.
The 22-year-old fourth seed will now face Shelby Rogers for a semi-final place after the American upset Czech sixth seed Petra Kvitova on Sunday.
Osaka is bidding for her third Grand Slam success after adding the 2019 Australian Open to her US Open title.
"It's quite easy to get down on yourself, especially when you feel like you could have already converted so many opportunities," said Osaka.
"I just told myself that she's a great player who's supposed to hold her serve, so just to keep pushing."
On her upcoming semi-final, Osaka - who lost her only previous Tour meeting against Rogers in 2017 - added: "I'm just going in there very optimistic.
"I might be the underdog because I've never beaten her. I'm just happy to still be here."