Her hand and her legs were shaking, she had missed nine match points but also saved six, and Anna Blinkova was 41 points into a wild tiebreaker that was the longest ever in a Grand Slam event.
Elena Rybakina, last year's Australian Open runner-up, was just as anxious on the other side of the net.
When Blinkova lunged to retrieve a backhand, aiming just to keep the rally alive, and Rybakina's next backhand sailed wide, it finished off a 6-4, 4-6, 7-6 (20) second-round victory Thursday that she will never, ever forget.
"It took me courage," Blinkova said. "It took me some certain calmness to stay in the present moment and to play point by point no matter what happens."
Rybakina, the 2022 Wimbledon champion who was runner-up in Melbourne last year to Aryna Sabalenka, saved two match points earlier in a third set that contained six service breaks.
Blinkova twice served for the match but couldn't finish the victory, and a double-fault in the 12th game sent it to a 10-point tiebreaker. Once there, 13 minutes after her first match points, Blinkova had two more points at 9-7, but again Rybakina saved them, and so it went on.
Blinkova, smiling, later described it as the "endless tiebreaker." It went on for 32 minutes until Rybakina's backhand error ended it.
In terms of points, at 42 it was the longest tiebreaker in a Grand Slam singles match, passing the 38-point tiebreaker between Lesia Tsurenko and Ana Bogdan at last year's Wimbledon and Jo-Wilfried Tsonga and Andy Roddick at the 2007 Australian Open.
"This day I'll remember for the rest of my life, on this court with this crowd, it's the best of my life so far," said Blinkova, shortly after she shared a hug with Rybakina at the net as the crowd gave the pair a standing ovation. "Thank you to the crowd for encouraging me. It gave me so much energy to fight until the end.
"It was super tough. I tried to stay focused on every point. I had so many match points and tried to be aggressive at these moments, but my hand was shaking and my legs too."
Rybakina became the fifth top-seeded woman to lose in the first two rounds. The five remaining top-10 women are the fewest in the third round of the Australian Open under the 128 main draw format (since 1988), according to ESPN Stats & Information.
The big-hitting Rybakina began the match sluggishly as Blinkova, her former doubles partner, capitalized with an early break before wrapping up the opening set.
The 25-year-old Blinkova built up the pressure and pounced on her opponent's serve again in the second set to take a 2-1 lead, but Rybakina responded with a break of her own to tie the set 4-4.
Rybakina shifted up a gear and drew level at one set apiece before the players traded breaks freely in the decider to set up their epic tiebreaker finish.
"I'm really proud that I could fight 'til the end," Rybakina said. "I mean, you can't always play perfect. And of course I could have lost it even earlier."
Blinkova equaled her best Grand Slam performance and will take on No. 26 Jasmine Paolini in the third round.
The Associated Press and Reuters contributed to this report.