Japan's Naomi Osaka reached her first Grand Slam quarter-final at the US Open on Monday, tearfully admitting she was prepared to "break a leg" to win the match.
The 20-year-old defeated Aryna Sabalenka of Belarus 6-3, 2-6, 6-4 to become the first Japanese woman in the US Open last-eight since Shinobu Asagoe in 2004.
Osaka, seeded 20, came back from a break down in the final set to take the tie on a fourth match point when Sabalenka served up an eighth double fault.
"I would never have forgiven myself if I had lost that match," said a tearful Osaka.
"When I was a break down in the final set I thought I would even break a leg if needed so I could get to every ball."
Next up for Osaka is a clash against Ukraine's 36th-ranked -- and fellow Grand Slam quarter-final debutant -- Lesia Tsurenko.
The 29-year-old had been on the brink of collapse due to heat exhaustion before seeing off Czech teenager Marketa Vondrousova 6-7 (3/7), 7-5, 6-2.
World number 36 Tsurenko was a set and 0-2 down when she bent double on the sizzling Grandstand court, looking increasingly unsteady in the 33-degree heat and crushing humidity.
"I was really dizzy and I asked nature or God or somebody please move the shade over faster," said the woman who put out world number two Caroline Wozniacki in the second round.
In the two-hour 32-minute match, which featured 13 breaks of serve, Tsurenko committed 57 unforced errors while 19-year-old Vondrousova hit a huge 73.
Osaka went into Monday's last-16 tie having won 22 games in succession at the tournament while fellow 20-year-old Sabalenka was on an eight-match win streak.
The 26th seed from Belarus was making her main draw debut in New York after a red-hot summer had seen her win a maiden title at New Haven and make the final in Cincinnati.
She had knocked out fifth seed Petra Kvitova, the two-time Wimbledon champion, in the third round.
However, Osaka broke twice in the first set and was looking comfortable for a fourth successive straight sets win at the tournament.
- Questions over Sharapova scheduling? -
Sabalenka roared back with breaks in the third and fifth games of the second set and was a break to the good in the decider at 2-1.
Osaka steadied the ship and retrieved the break immediately.
Sabalenka saved three match points from 0-40 in the 10th game but her eighth and final double fault sealed her fate.
Also making the last eight was 2017 runner-up Madison Keys who eased to a 6-1, 6-3 win over Slovakia's Dominika Cibulkova.
American 14th seed Keys, who was defeated by compatriot Sloane Stephens in the 2017 championship match, fired 25 winners to Cibulkova's seven.
The 23-year-old will face either former champion Maria Sharapova or Spain's Carla Suarez Navarro for a place in the semi-finals.
"I am really glad I got the win," said Keys after reaching her third Grand Slam quarter-final of the season.
"Dominika is a good player so even though I was a set and 2-0 ahead, it wasn't surprising that she would come back and win a few games."
Sharapova, the 2006 champion, will attempt to return to the quarter-finals for the first time since 2012 when she faces Suarez Navarro.
The five-time Grand Slam winner has a flawless 23-0 record under the lights at Flushing Meadows.
However, eyebrows have once again been raised over the scheduling of her matches.
All four Sharapova ties this year will have been at night -- three on Arthur Ashe and one on the adjacent Louis Armstrong.
Even six-time champion Serena Williams has had to play one match in the afternoon.
"It is very unfair. There are rules and then there are rules for certain players," former tour player Daniela Hantuchova told broadcaster Amazon Prime.
"I spoke to Carla's coach and he couldn't believe it is not a day session match."
The two other quarter-finals will feature Williams against Karolina Pliskova, the Czech eighth seed, while third seed Stephens faces Latvia's Anastasija Sevastova.