Naomi Osaka tearfully admitted she was prepared to "break a leg" to defeat Aryna Sabalenka as she reached her maiden Grand Slam quarter-final at the US Open.
The Japanese player recovered from a break down in the third set to beat her fellow 20-year-old 6-3 2-6 6-4 in a high-quality fourth-round encounter at Flushing Meadows.
Osaka, seeded 20th, secured victory on her fourth match point as the in-form Sabalenka double faulted for the eighth time in the match.
"I would never have forgiven myself if I had lost that match today," said an emotional 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."
Osaka came into the match having won 22 games in succession at the tournament while Sabalenka, who won her first title at New Haven last month, was on an eight-match winning run.
After the opening two sets had been traded, Sabalenka, making her main draw debut, appeared to have gained the upper hand by moving a break to the good at 2-1 in the decider but Osaka hit back immediately.
Osaka, who becomes the first Japanese woman in the US Open last-eight since Shinobu Asagoe in 2004, saw three match points come and go in the 10th game but a costly double fault from her opponent proved decisive.
The world No 19 will now meet unseeded Lesia Tsurenko on Wednesday after the Ukrainian defeated Czech teenager Marketa Vondrousova 6-7 (3-7) 7-5 6-2.
Tsurenko recovered from fatigue due to heat exhaustion when trailing by a set and 2-0 to reach also reach a Grand Slam quarter-final for the first time in her career after a two-hour and 32-minute encounter which featured 13 breaks of serve.
Another player to reach the quarter-finals was Madison Keys as the American home favourite secured a convincing 6-1 6-3 victory against Dominika Cibulkova to maintain her hopes of a maiden Grand Slam title.
The 23-year-old, who had similar issues in his first-round victory against Marton Fucsovics, hit 26 winners and 6 aces as she dominated the Slovakian 29th seed in a one-sided encounter on Arthur Ashe Stadium.
Keys had never lost to Cibulkova in their previous four meetings and despite being pushed harder in the second set upper her game once again to progress on Labor Day.
The American, who has only dropped one set from her opening four matches, will meet either 2006 champion Maria Sharapova or Spain's 30th seed Carla Suarez Navarro.
Keys won a 14-minute long second game of the match on the Cibulkova serve before running away with the first set.
Cibulkova was once again broken at the start of the second set but after coming through a tough serve hole trailing 2-0 got back to parity with her first break of the match as Keys committed some unforced errors.
But Keys regained the momentum with another break at 3-3 and continued to use her aggressive baseline game to good effect to wrap up victory with her fourth break of the match.
"I am really glad I got the win," Keys said 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.
"So I just had to focus on getting some first serves in and wait for the right ball."
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Tennis is back on Sky Sports screens with the Laver Cup in September while we will also have coverage of the ATP Finals in November with every match live on Sky Sports. But first, we will be across the final major of the year in New York as the US Open right through to the final with live blogs, reports, features and reaction.