NEW YORK — Canada's Leylah Fernandez continued her remarkable run at the U.S. Open Tuesday, earning a spot in the semifinals with an upset victory over Elina Svitolina of Ukraine.

The 19-year-old from Laval, Que., held on through some difficult stretches to post a 6-3, 3-6, 7-6(5) win over the tournament's No. 5 seed.

Fernandez, ranked 73rd in the world and participating in only the seventh major tournament of her career, broke Svitolina midway through the first set and won 4-of-10 break points across the two-hour-and-24-minute match.

“I obviously have no idea what I’m feeling right now,” said Fernandez. “I was so nervous. I was trying to do what my coach told me to do.”

That coach is her father, who isn’t in New York — he stayed home and is offering tips in daily phone conversations. That helps, certainly, as does the loud backing she’s been receiving from the spectators, who rose and cheered wildly each time Fernandez raised a fist high above her head or wind-milled both arms after winning a key point in Arthur Ashe Stadium.

“I called him right after the match, when I went to the locker room,” she said. “He honestly told me that I put him through hell and back with this match.”

Svitolina, who won bronze at the Tokyo Olympics last month, had eight aces and won 72 per cent of her first-serve points, but the Canadian remained patient and agile, dashing across the court to place shots just beyond her opponent's reach.

"She did a lot of things well," ESPN tennis analyst Pam Shriver said about Fernandez. "Her lefty serve is causing a lot of awkward return positions where Svitolina just struggled in the first set.

"How quickly Fernandez takes the ball on the baseline is causing problems for people (and) the angles she's able to come up with on both the forehand and the backhand."

Fernandez, currently ranked No. 73 in the world, also beat stars Naomi Osaka of Japan in the third round and Germany's Angelique Kerber in the fourth.

In the semifinals she'll face No. 2 seed Aryna Sabalenka of Belarus, a Wimbledon semifinalist in July, who defeated French Open champion Barbora Krejcikova 6-1, 6-4.

Meanwhile, Montreal's Felix Auger-Aliassime, the No. 12 seed joined Fernandez in the semifinals on the men's side later Tuesday after his opponent Carlos Alcaraz of Spain retired in the second set.

The 21-year-old Auger-Aliassime was up 6-3, 3-1 when 18-year-old Alcaraz waved over his trainer before calling an end to his tournament.

Auger-Aliassime will face No. 2 seed Daniil Medvedev in the semifinals.

Medvedev, a 25-year-old from Russia, earned a spot in the final four at Flushing Meadows for the third consecutive year by stopping the surprising run of Dutch qualifier Botic van de Zandschulp 6-3, 6-0, 4-6, 7-5.