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 at a ninth consecutive Grand Slam event.

Sinner struggled two days previously with the extreme heat and suffered from cramps in his 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.

On the women's side, Iga Swiatek ruthlessly ended home hopes at Melbourne Park by dispatching qualifier Maddison Inglis 6-0, 6-3 to reach the last 8 and continue her quest for a maiden Australian Open title to complete a career Grand Slam.

Inglis, 28, had reached the fourth round after her third-round opponent Naomi Osaka pulled out of the Grand Slam due to an abdominal injury.

The World No. 168 was the final Australian in the women's singles draw.

Swiatek, who needed three sets to beat Russian Anna Kalinskaya in the previous round, produced a strong performance to defeat Inglis, firing off 22 winners.

"I felt pretty confident from the beginning. It felt like the pace of the ball was lot different from my last round. So I needed to adjust with my legs and really be precise with the footwork," the Polish World No. 2 said.

She whitewashed Inglis in the opening set, with her powerful baseline returns and movement proving too much for the Australian to handle.

Though Swiatek suffered a break in the opening game of the second set, she ratcheted up the intensity and wrapped up the win in an hour and 13 minutes to enter her third Australian Open quarterfinal where she will face 2022 Wimbledon winner Elena Rybakina of Kazakhstan.