"I'm sad," Sakkari said. "I'm very broken that I couldn't make it to my first final, once again. But I'm positive that it will come sometime soon." Wimbledon was Raducanu's only previous major tournament; she entered via a wild-card entry with a ranking outside the top 300 and made it to the fourth round before stopping in the second set because of trouble breathing. Fernandez's best past showing at a Slam was getting to the third round at Roland Garros last year.

At the outset Thursday, Sabalenka looked in control, claiming 12 of the first 14 points for a 3-0 lead. Just eight minutes had elapsed and most spectators were yet to reach their seats. Not until later did the 20,000-plus in the stands rally the fist-aloft Fernandez with chants of "Let's go, Leylah! Let's go!" accompanied by rhythmic clapping.

"I'm glad that whatever I'm doing on court, the fans are loving it — and I'm loving it, too," Fernandez said. "We'll say it's magical." At the end of the first set and again the third, it was Sabalenka who let things get away from her. In the last game, she double-faulted twice in a row to set up match point, then sailed a forehand long.

"This," Sabalenka said, "is what we call pressure." No matter what, seemingly, Fernandez did not feel it. Didn't waver. And why would she at this point? Her poise, much like Raducanu's, is as limitless as their potential.

This was the left-handed Fernandez's fourth consecutive three-set victory over a seeded opponent. First came No. 3 Naomi Osaka, the 2018 and 2020 US Open champion. Then came No. 16 Angelique Kerber, the 2016 champ. That was followed by No. 5 Elina Svitolina and Sabalenka.

"There's no limit to what I can do. I'm just glad that right now everything's going well," said Fernandez, who could give Canada its second US Open women's title in quick succession, following Bianca Andreescu's triumph in 2019.

Raducanu and Fernandez are both very much citizens of the world.

Raducanu was born in Toronto to a Chinese mother and Romanian father; the family moved to England when Emma was 2.

Fernandez was born in Montreal to a Filipino Canadian mother and Ecuadorian father; the family moved to Florida after Leylah had success as a junior at age 12. Dad is also her coach, although he is not with her in New York, instead offering coaching tips in daily phone conversations.

Perhaps he told his daughter to let Sabalenka make all the mistakes in a tiebreaker, because that's what happened at the conclusion of the first set. Sabalenka went up 2-0 and then completely lost her way. Every point won by Fernandez came courtesy of a miss by Sabalenka.

"I wouldn't say that she did something," Sabalenka said. "I would say that I destroy myself." In the second set, Sabalenka regained her form and Fernandez took a step back. But by the third, it was Fernandez's time to shine. "Now she's like (a) top-10 player," Sabalenka said. "We'll see how good she will be in the future." Raducanu and Fernandez met each other for the first time when they were both playing in under-12 tournaments and bonded over their shared connection to Canada. On Saturday, they will share a court for the first time in a tour-level match. They did play, however, in the Wimbledon junior tournament's second round in 2018.

Raducanu won that one. Three years later, they'll play again — on a grander stage and with much, much more at stake.