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.

The scoreline was harsh on the youngster, who was very competitive in the 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.

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