Canadian Leylah Fernandez, 19, is into the US Open semi-finals on the back of a 6-3, 3-6, 7-6(7/5) win over Ukrainian fifth seed Elina Svitolina.
Fernandez surrendered a 5-2 lead in the third set, as the sheer importance of the moment seemed to get to her for the first time against the more-seasoned Svitolina.
The Ukrainian got back to 5-5 and then 6-6 to force the tie-break, but it was Fernandez who showed the most composure in the biggest moment, to advance to her first major semi-final.
At 5-5 in the breaker, Fernandez produced her 37th winner, with a forehand pass down the line and the net cord helping the ball fly over Svitolina's racket.
Fernandez served out the match on the next point.
With no US players in the quarter-finals of the singles at their home slam for the first time, the Canadian contingent of Fernandez and Felix Auger-Aliassime are enjoying the favouritism of the Flushing Meadows crowd desperate for North American success.
"I honestly have no idea what I'm feeling right now," Fernandez said.
"Throughout the whole match I was so nervous. Thanks to you guys, to the New York crowd cheering me on, fighting for me and never giving up for me. Thanks to you, I was able to push through today."
While not necessarily a household name, Svitolina is a regular presence in the second week of slams, competing in her eighth major quarter-final since 2015, with semi-finals at Wimbledon and the US Open in 2019 on her CV.
She has also been ranked as high as three in the world and has been one of the form players of the women's tournament for two years.
The Ukrainian is the third major victim of Fernandez's brilliance, after defending champion Naomi Osaka and three-time slam winner Angelique Kerber fell in the previous two rounds.
Next up will be Belarusian world number two Aryna Sabalenka, who defeated Czech eighth seed Barbora Krejcikova 6-1, 6-4.
However, based on her quarter-final performance, Fernandez may still be the favourite going into that clash.
Her speed made her almost impossible to pass at the back of the court and she found the line with seemingly every groundstroke.
Svitolina entered the match having not lost a set at this year's tournament and coming off a win over former world number one Simona Halep, but Fernandez immediately spoiled the Ukrainian's perfect record in New York thanks to a 13-4 advantage on winners in the first set.
While Svitolina appeared to have turned the tide when she stormed to a 5-1 lead in the second set, Fernandez won a break and held form as a reminder that she was not going away.
That form also gave her some much-needed momentum heading into the third.
Fernandez led the deciding set 5-2 and served for the match at 5-3 but showed her first sign of nerves, while Svitolina applied the pressure from the back of the court to break back at the most important moment.
Svitolina held serve to get back to 5-5, with the weight of expectation now on Fernandez at just her second US Open.
Struggling to land a penetrating first serve, Fernandez faced deuce but found a stunning backhand down the line to get the advantage, winning the game and forcing Svitolina to once again play from behind at 5-6.
Typical of the two-and-a-half-hour match, where neither player had the upper hand for more than a game or two, the Ukrainian again dug deep and forced the match into a tie-break with a steely service hold.
The deciding tie-breaker was a fittingly close affair, with the crowd sent into raptures when Svitolina's return sailed long, handing Fernandez the match.
One more teenager could also reach the women's semi-finals, with British 18-year-old Emma Răducanu set to face 11th seed Belinda Bencic on Thursday morning (AEST).
Medvedev rolls on, awaiting another youngster
On the men's side of the draw, Daniil Medvedev reached the US Open semi-finals for the third straight year, ending the surprising run of qualifier Botic van de Zandschulp with a 6-3, 6-0, 4-6, 7-5 victory.
Like Svitolina, the Russian second seed dropped a set for the first time in the tournament but he recovered to keep alive his bid for his first major title after coming close a number of times.
Medvedev fell to Rafael Nadal in a five-set final in 2019, before losing to eventual champion Dominic Thiem in last year's semi-finals.
The 25-year-old also lost to Novak Djokovic in the final of this year's Australian Open.
"I just want to do a little bit better than [the] last two times and get this last step, which is the toughest one actually," Medvedev said.
His quarter-final could not have started much easier, breaking six times in Van de Zandschulp's first eight service games and winning the second set to love in just 22 minutes.
Van de Zandschulp was trying to become the first man to come through the qualifying rounds to reach the US Open semi-finals, and the first man to reach the semis in his tournament debut, since 1948.
But the 25-year-old from the Netherlands, who had never even been to New York before the tournament, was completely outplayed early, disappointing his orange-clad fans inside Arthur Ashe Stadium.
Despite being visibly exhausted, Van de Zandschulp rode an excellent serving performance to win the third set before Medvedev closed out the match in the fourth.
Medvedev will play 12th-seeded 21-year-old Auger-Aliassime in the semi-finals after 18-year-old Carlos Alcaraz of Spain withdrew from their match in the second set.
AP/ABC
