The Associated Press Aryna Sabalenka celebrates after defeating Iva Jovic of the U.S. in the quarterfinals early today.

MELBOURNE, Australia — Top-seeded Aryna Sabalenka beat 18-year-old American Iva Jovic 6-3, 6-0 early today to reach the semifinals at the heat-affected Australian Open.

The match at Rod Laver began with the roof open as heat warnings hit Melbourne with temperatures expected to be above 40 Celsius (104 Fahrenheit). The roof stayed open for that match but was closed for the following men’s quarterfinal between Alexander Zverev and American Learner Tien.

Sabalenka, who is trying to win her third Australian title in four years, went up 3-0 in the first set and established her dominance early against the 29th-seeded Jovic. But Jovic stayed in the set and had three breakpoint chances in the ninth game, which lasted 10 minutes.

Sabalenka raced to a 5-0 lead in the second set with two breaks, taking any momentum away from the young American. Jovic didn’t help herself near the end of the match, double-faulting on break point to give Sabalenka her 5-0 lead.

In the final game, Sabalenka served an ace on break point and clinched it with another ace on match point. She saved all five break points she faced and had seven aces.

Sabalenka defeated 19-year-old Canadian Vicky Mboko to reach the match against another teenager.

“These teenagers have tested me in the last couple of rounds — incredible player,” Sabalenka said of Jovic in an on-court interview.

“It was a tough match,” Sabalenka added. “Don’t look at the score, it wasn’t easy at all. She played incredible tennis and she pushed me to a one-step better level. It was a battle.”

Sabalenka won in 2023 and 2024 and was the runner-up a year ago to Madison Keys. Keys was knocked out of the tournament on Monday by fellow American Jessica Pegula.

Jovic was born in California and is the daughter of parents who immigrated to the United States. Her father is Serbian and her mother Croatian and Jovic has been getting tips from Serbian star Novak Djokovic.

Sinner streak at 18

Jannik Sinner wasn’t shaky or lucky to survive this time and the only thing really hot on Monday was his streak, which now stands at 18 straight wins at the Australian Open.

The two-time defending champion had a 6-1, 6-3, 7-6 (2) win over fellow Italian Luciano Darderi to reach the quarterfinals for a ninth consecutive Grand Slam event.

Sinner struggled two days previously with the extreme heat and cramping in the afternoon win over No. 85-ranked Eliot Spizzirri, when he only took control after the roof was closed.

In an evening match in cooler conditions, Sinner was cruising until Darderi lifted his tempo in the third set. Second-ranked Sinner missed match points in the 10th game on Darderi’s serve but then took it up a notch in the tiebreaker.

“I felt quite good out there physically. Everything was okay today,” said Sinner, who had limited practice on his off day between his third and fourth-round matches. “Let’s see what’s coming in the next round.”

It’ll be a familiar foe. No. 8-seeded Ben Shelton beat No. 12 Casper Ruud 3-6, 6-4, 6-3, 6-4 in a night match on Rod Laver Arena.

Sinner has won his last eight meetings with the 23-year-old American, including their semifinal here last year.

“I have a lot more that I want to do here, and I’ve got a lot to prove,” Shelton said. “I’ll be ready to go.”

Sinner, toward the end of his first official head-to-head with Darderi, had to improve to handle the sudden increased speeds of his rival’s forehand.

Darderi saved two match points on his serve in the 10th game of the third set and took the first two points of the tiebreaker. He had to pause for a few moments then before serving because of a baby crying in the crowd at Margaret Court Arena.

He didn’t win another point. Sinner reeled off the next seven to triumph in 2 hours and nine minutes.