Tennis-Barty
World No.1 Ashleigh Barty of Australia returns a shot en route to her win over Aryna Sabalenka of Belarus during their Miami Open match at Hard Rock Stadium on Tuesday. Image Credit: AFP

Miami: Aryna Sabalenka clearly laboured in the final set of her match. Frances Tiafoe seemed to barely have the energy needed to reach the post-match handshake.

Conditions were tough at the Miami Open.

The top seeds, however, were up to the challenge.

World No. 1 Ash Barty of Australia won the final nine points to finish off the seventh-seeded Sabalenka in a three-set women’s quarterfinal Tuesday, while men’s top-seeded Daniil Medvedev of Russia reached the quarters with a straight-set win over Tiafoe - part of a day where the American men’s contingent was pared from four to one, with Sebastian Korda the lone round-of-16 survivor for the US.

The 20-year-old Korda stunned fifth-seeded Diego Schwartzman of Argentina 6-3, 4-6, 7-5 for the biggest win of his career to date. And it’ll make for an interesting Thursday for the Korda family: he’ll be in the Miami quarter finals that day while his sisters, Jessica and Nelly, will be playing in the first round of the first women’s golf major of the year, the ANA Inspiration.

MORE ON TENNIS

‘‘Sebi is a guy who is going to be special, man,” Tiafoe said.

Korda, whose father Petr Korda reached No. 2 in the world during his stellar career, put on a show to delight the evening crowd. He was broken at 5-4 in the third to give Schwartzman hope, then responded by breaking the Argentine right back and finally serving out the match.

By then, it was maybe a bit cooler than the brutal conditions that players endured in the day session - but still tough, which Korda appreciated.

‘‘I love the heat and I love the humidity. The hotter it is, the more humid it is, the happier I am,” said Korda, who faces fourth-seeded Andrey Rublev of Russia in the quarterfinals. Rublev beat Marin Cilic 6-4, 6-4 on Tuesday night.

After some early clouds cleared out and bright sunshine starting pounding down, the mid-afternoon temperature reached the mid-80s Fahrenheit (upper 20s Celsius) at Hard Rock Stadium and the humidity made it feel even hotter.

Barty didn’t wilt, ousting Sabalenka 6-4, 6-7 (5), 6-3 for her third three-set win in four matches at the tournament. Medvedev beat Tiafoe 6-4, 6-3, and has gone 10-1 in sets against the American in their past four head-to-head matchups.

‘‘Everywhere in the world there are different conditions and at times it suits you more than other places,’’ Barty said. ‘‘I feel like these are very familiar conditions for me. With the heat and humidity, it’s very similar to Brisbane where I grew up and what I was born and bred and trained in my whole life.’’

Barty faced seven break points in the match and saved them all. She’ll meet No. 5 seed Elina Svitolina in Thursday’s semi-finals. Svitolina eased past Anastasija Sevastova 6-3, 6-2 on Tuesday night to make the final four in Miami for the first time.

Results

Men

4th round

Daniil Medvedev (RUS x1) bt Frances Tiafoe (USA) 6-4, 6-3

Roberto Bautista Agut (ESP x7) bt John Isner (USA x18) 6-3, 4-6, 7-6 (9/7)

Jannik Sinner (ITA x21) bt Emil Ruusuvuori (FIN) 6-3, 6-2

Alexander Bublik (KAZ x32) bt Taylor Fritz (USA x22) 6-7 (5/7), 6-3, 6-4

Hubert Hurkacz (POL x26) bt Milos Raonic (CAN x12) 4-6, 6-3, 7-6 (7/4)

Sebastian Korda (USA) bt Diego Schwartzman (ARG x5) 6-3, 4-6, 7-5

Stefanos Tsitsipas (GRE x2) bt Lorenzo Sonego (ITA x24) 6-2, 7-6 (7/2)

Andrey Rublev (RUS x4) bt Marin Cilic (CRO) 6-4, 6-4

Women

Quarter-finals

Ashleigh Barty (AUS x1) bt Aryna Sabalenka (BLR x7) 6-4, 6-7 (5/7), 6-3

Elina Svitolina (UKR x5) bt Anastasija Sevastova (LAT) 6-3, 6-2