Aryna Sabalenka ended the teenage challenge at the Australian Open with an emphatic quarter-final final victory over Iva Jovic as the tournament's 'Heat Stress Scale' reached the highest threshold of 5.0 with temperatures breaking 40 degrees.
Having defeated 19-year-old Victoria Mboko in the fourth round, the world No 1 dropped just three games against 18-year-old American Jovic in a 6-3 6-0 victory.
Elina Svitolina upset Coco Gauff 6-1 6-2 to move into her first semi-final in Melbourne, where she will meet Sabalenka.
Jovic was very competitive in points but time and again came out on the wrong end of games.
It has nevertheless been a breakthrough tournament for Jovic, who only celebrated her birthday last month, and she will hit the top 20 for the first time next month.
"These teenagers are testing me in the last couple of rounds," said Sabalenka, who has now reached at least the semi-finals at 12 of the last 13 Grand Slams she has contested.
"She's an incredible player, it was a tough match - don't look at the score, it wasn't easy at all. I'm super happy with the win, it was a tough battle."
With the hottest day in Melbourne for 17 years forecast and temperatures set to reach around 45C, efficiency was of the essence for Sabalenka, who is yet to drop a set.
Things might have become more complicated had she not clinched the opening set in a long ninth game, saving three break points before clinching her third set point.
After that, she did not lose another game, and the roof closed on Rod Laver Arena as Sabalenka conducted her post-match interview, with the tournament's heat stress scale hitting the cut-off mark of five shortly before 1.30pm.
"At the end of the match, it was really hot out there," said the 27-year-old. "I'm glad they closed the roof almost halfway so we had a lot of shade in the back."
Sabalenka added with a smile: "I guess, as a woman, we are stronger than the guys, so they had to close the roof for the guys so they don't suffer.
"I knew going into this match that they won't let us play in crazy heat. If it would reach the five, they would definitely close the roof, so I knew that they were protecting us, our health. It's okay. I'm happy that I managed."
Organisers had reworked the schedule in anticipation, with the start of the wheelchair draws postponed until Wednesday and junior matches beginning at 9am.
The later junior matches were scheduled not before 6.30pm, and all the day matches had finished before the most serious heat rules were implemented, which would have seen matches postponed on uncovered courts.
The heat stress scale takes into account air temperature, radiant heat, humidity and wind speed to determine when conditions are safe for players.
With husband Gael Monfils supporting from the sidelines, Svitolina produced a strong display of consistent tennis, but she was given more than a helping hand by Gauff, whose tally of three winners compared to 26 unforced errors told its own story.
The American has struggled since winning her second Grand Slam title at the French Open last year, particularly with her serve, and she was filmed behind the scenes repeatedly smashing her racket after the loss.
The result meant 12th seed Svitolina marched into the semi-finals here for the first time in her career and her fourth Grand Slam semi-final overall. It's also her second since she returned to the tour following the birth of daughter Skai in 2022, with the former world No 3 making an emotional run at Wimbledon the following year.
Gauff's service woes came to the fore early in the contest as she made five double faults and was broken four times to let the aggressive Svitolina take full advantage and grab the opening set in double quick time.
Desperate to arrest her slide, the American sent a bunch of rackets to be re-strung for cooler conditions under the roof on Rod Laver Arena after organisers earlier invoked their extreme heat policy on a scorching afternoon.
Svitolina raced to a 3-0 lead in the second set before Gauff was able to get on board with a couple of holds, but there was no stopping the Ukrainian, who eased to victory.
"This means the world to me, and of course I try to push myself, give myself the motivation to continue, and I'm very pleased with this performance in Australia," said Svitolina, who made it 10-0 in 2026.
"Overall it's been a good trip for me and I'm really happy to go through to my semi-final!
"I'm very, very pleased with the tournament so far, and of course it's always been my dream to come back after maternity leave and make the top 10 again. It's always been my goal, and now I have it.
"Unfortunately, it didn't happen last year, but it's happened now.
Six-time Grand Slam semi-finalist Tim Henman speaking on TNT Sports:
"We all have bad days at the office, but in the context of being the favourite going into that match, Gauff's a Grand Slam champion, won the French Open, won the US Open, she's No 3 in the world, that was a shocking performance.
"There's no two ways about it. Svitolina just took advantage.
"But when you get a top player, who can really only kick that first serve in - she was serving at 125 kmph, and then making so many mistakes from the back of the court. The assets of her game were completely stripped apart in front of our eyes.
"That was pretty tough to watch."
Doubles specialist Jamie Murray speaking on TNT Sports:
"Svitolina played a very solid match, she took off from where she left against Andreeva.
"It was a very disappointing performance from Coco Gauff. She rightfully took it out on the racket in the tunnel at the end of the match.
"The more you think technically on the court, the more rigid and stiff you can become. Your strokes and footwork go."
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