American Marconi Wireless News - Sabalenka powers into semi-finals as Melbourne braces for 45C

World number one Sabalenka tamed 18-year-old American Iva Jovic 6-3, 6-0 and faces either third seed Coco Gauff or 12th seed Elina Svitolina for a place in the final.

Sabalenka, the top seed from Belarus, is aiming to win a third Melbourne crown in four years and looks in ominous form, yet to drop a set.

"These teenagers have been testing me in the last couple of rounds," said Sabalenka, 27, who is on a 10-match win streak after victory in Brisbane this month.

"It was a tough match. Don't look at the score, it wasn't easy at all.

"She played incredible tennis. Pushed me to one step better level. And I'm super happy with the win."

The match was played in hot sun on Rod Laver Arena, as temperatures reached 38C.

Just after the match, organisers closed the roof, meaning the other three quarter-finals will take place in far more comfortable temperatures.

The decision came after the tournament hit its maximum "heat stress" rating of five for the second time in four days.

The measure is designed to protect players, fans and officials.

Play on outdoor courts, which were to host junior boys' and girls' matches, were put on hold.

Temperatures reached 40C on Saturday, with matches on outside courts paused for about five hours.

Defeat brought an end to a breakthrough tournament for Jovic, the youngest player in the women's top 100 and seeded 29.

She stunned seventh seed and two-time Slam finalist Jasmine Paolini and blitzed past experienced Yulia Putintseva for the loss of just one game to announce herself to the world.

But Sabalenka was a bridge too far.

- Alcaraz in home test -

Alcaraz faces having to beat not just Alex de Minaur but also a patriotic home crowd to make his first Australian Open semi-final.

Whoever comes out on top will meet German third seed Alexander Zverev, who lost the final last year to Jannik Sinner, or American next-gen star Learner Tien.

The 22-year-old Spaniard Alcaraz has won six Grand Slams, but is yet to go past the last eight in Melbourne.

De Minaur has failed to make it past the quarter-finals at any Slam and is hoping the home fans can help him pull off an upset in the last match of the day on centre court.

"For me, it just comes down to I'm going to have to bring some of my best tennis," said the Australian, who has lost all five previous encounters with Alcaraz.

"Once I rock up on Tuesday and I walk on court, you just deal with whatever's in front of you," he added of the prospect of a closed roof.

O.Johnson--AMWN