MELBOURNE, Australia — 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.''