MELBOURNE, Australia — Elina Svitolina ended 15-year-old Marta Kostyuk’s run at the Australian Open, met her at the net for a warm embrace and offered some words of encouragement.
With the temperature hitting 40 Celsius (104 Fahrenheit) for the second straight day, fourth-seeded Svitolina reached the fourth round at the season-opening major for the first time with a 6-2, 6-2 win on Rod Laver Arena.
‘‘It was sad playing another Ukrainian girl, same country is always tough,’’ Svitolina, one of five women in contention for the No. 1 ranking, said. ‘‘She’s a great fighter. She has a great future — we’re going to hear a lot more about her.’’
Kostyuk entered the tournament ranked No. 521 — a number that will likely be halved next month — and had wins over 25th-seeded Peng Shuai and Olivia Rogowska to become the youngest player to win main-draw matches at the Australian Open since Martina Hingis in 1996.
The step up to facing a top 10 player was too much for Kostyuk on Friday.
She had nine double faults, including on match point, and only got 37 percent of her first serves into play.
Svitolina, the only seeded player still in contention in her quarter, had five aces, only 11 unforced errors and didn’t serve a double fault in the 59-minute match.
Kostyuk sobbed into a towel in the tunnel soon after leaving the court, but could joke about the defeat when asked later what she could take out of the experience.
‘‘Well, a lot,’’ she said. ‘‘How much you have to pay Svitolina to have one-hour lesson? I got it for free.’’
Kostyuk received entry into qualifying because of her junior girls’ victory last year at the Australian Open. She won all three qualifying matches, then her first two in the main draw.
Svitolina will next play Denisa Allertova, who beat Magda Linette, 6-1, 6-4.
In the opening match on Rod Laver Arena, Petra Martic celebrated her 27th birthday with a 6-3, 3-6, 7-5 over Thai qualifier Luksika Kumkhum.
‘‘That was really ugly,’’ Martic said of the heat. ‘‘We were lucky to play on Rod Laver because we had some shade behind so you could hide for a few seconds in between the points.
‘‘Other than that, it’s just, you just need to be mentally tough and ready to just suffer out there.’’
Elise Mertens needed four match points before clinching a 7-5, 6-4 win over Alize Cornet, who needed a medical time out in the second set after complaining of being short of breath. After having her blood pressure taken and being draped in ice towels, she was able to continue and play seven more games.
Mertens will meet Martic in the next round.
The temperature was forecast to hit 42 C (108 F) but a weather change in the afternoon eased conditions slightly.
Kyle Edmund was the first man into the fourth round, overcoming Nikoloz Basilashvili, 7-6 (7-0), 3-6, 4-6, 6-0, 7-5 in 3½ hours on open court in the peak of the heat.
No. 10 Pablo Carreno Busta had a 7-6 (7-4), 4-6, 7-5, 7-5 win over No. 23 Gilles Muller.