Australian Open: Rafael Nadal, Grigor Dimitrov enter 4th round

The heat wasn't a factor for Rafael Nadal this time against Damir Dzumhur, despite the searing temperature causing trouble for players earlier Friday at the Australian Open.

Nadal reached the fourth round in Australia for the 11th time with the 6-1, 6-3, 6-1 win, and leveled his career head-to-head record with Dzumhur.

The 16-time major winner lost their only previous meeting when he had to retire because of heat-related issues in the third set at Miami in 2016, giving Dzumhur the win that day.

It was also a change of scenery for Nadal, who was playing on Margaret Court Arena — the No. 2 venue at Melbourne Park — while local hope Nick Kyrgios played Jo-Wilfried Tsonga in a night match at Rod Laver Arena.

The youngest player in the tournament and the oldest player in the men's draw went out earlier on Day 5.

Fourth-seeded Elina Svitolina ended 15-year-old Marta Kostyuk's run with a 6-2, 6-2 victory, then met her fellow Ukrainian at the net for a warm embrace and some words of encouragement.

"She's a great fighter," Svitolina, one of five women in contention for the No. 1 ranking, said of her fellow Ukrainian. "We're going to hear a lot more about her."

Andreas Seppi withstood 52 aces from 38-year-old Ivo Karlovic for a 6-3, 7-6 (4), 6-7 (3), 6-7 (5), 9-7 win in 3 hours and 51 minutes in an afternoon match.

Players were bothered and spectators clamored for shade and mist-spraying fans in searing heat earlier Friday, and organizers were on the verge of enforcing the tournament's extreme heat policy before temperatures dropped significantly after peaking around 2 p.m. local time.

Play can be suspended at the Australian Open if the temperature 40 Celsius (104F) and a combination of factors — including temperature, humidity and breeze — reaches an unbearable limit.

Alize Cornet, who needed a medical timeout and a doctor to take her blood pressure as she struggled with heat stress in her 7-5, 6-4 third-round loss to Elise Mertens, was among those suggesting the extreme heat policy needs reviewing.

"I started to feel dizzy. ... I was feeling super, super hot. I kind of felt that I could faint at any moment," she said, adding that while precautions were taken by tournament officials, "playing in this condition is of course very dangerous for the health of the player.

"The limit of not playing the match is really high. ... I think this limit should be a little bit lower."

No. 3-seeded Grigor Dimitrov beat No. 30 Andrey Rublev 6-3, 4-6, 6-4, 6-4 in just over three hours after the change came through and said "the heat didn't scare me at all today."

Kyle Edmund overcame Nikoloz Basilashvili 7-6 (0), 3-6, 4-6, 6-0, 7-5 in 3 ½ hours on an open court in the peak of the heat, earning a spot in the next round against Seppi. No. 10 Pablo Carreno Busta had a 7-6 (4), 4-6, 7-5, 7-5 win over No. 23 Gilles Muller.

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.

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, who had nine double-faults — including one on match point — 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."

Svitolina will next play Denisa Allertova, who beat Magda Linette 6-1, 6-4. No. 19 Magdalena Rybarikova had a 7-5, 3-6, 6-1 win over Kateryna Bondarenko.

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, you need to be mentally tough and ready to just suffer out there."