Spanish sensation Carlos Alcaraz has flexed his muscles at Melbourne Park with an entertaining four-set victory to equal an Australian Open personal best.
The two-time grand slam champion was challenged by Italian Lorenzo Sonego on Thursday, conceding the second set before moving on with a 6-4 6-7 (3-7) 6-3 7-6 (7-3) victory.
Alcaraz's brute strength and incredible shot-making were on full show to the Rod Laver Arena crowd, as the three-hour and 25-minute spectacle bled into the night session.
"I'm really happy with my performance today," the 20-year-old said after making an outrageous round-the-net shot at 3-3 in the second set on his way to notching his 200th tour-level match.
"The match was a little bit tricky with the wind and the sun ... it was tough to bring your best."
The result equals his best result at Melbourne Park, a third-round exit in 2022.
Alcaraz has reached at least the semi-finals in the other three majors, winning the US Open in 2022 and Wimbledon in 2023 as he became world No.1.
The second seed can recapture top spot from Novak Djokovic with this year's Australian Open crown, after missing the 2023 tournament through injury.
The Spaniard next faces 18-year-old Chinese wildcard Juncheng Shang, who ended Indian qualifier Sumit Nagal's tournament 2-6 6-3 7-5 6-4.
In another late night epic that stretched for nearly four-and-a-half hours until 3.40am, Daniil Medvedev, the No.3 seed, was left mightily relieved to come from two sets down against Finland's Emil Ruusuvuori and progress with a 3-6 6-7 (1-7) 6-4 7-6 (7-1) 6-0 triumph.
Much, much earlier, Olympic champion Alexander Zverev had snatched victory from the jaws of defeat with a five-set marathon win over Lukas Klein.
In a see-sawing second-round encounter on John Cain Arena, Zverev was two points away from elimination when serving to stay in the match at 5-6 in the fifth set, but held his nerve to oust the Slovakian qualifier 7-5 3-6 4-6 7-6 (7-5) 7-6 (10-7).
The pair traded blows for four hours and 30 minutes, before the German star won out in a nail-biting super tiebreak.
"To be honest, he probably deserved to win the match more than me today," Zverev said of the world No.163.
The German let out a pressure-relieving scream after booking a third-round clash with American Alex Michelsen, a 4-6 6-3 6-4 6-4 winner over Czech No.32 seed Jiri Lehecka.
Zverev came under scrutiny this week when German news outlets reported he would stand trial in May, during the French Open, after he was ordered to pay fines of 450,000 Euro ($A750,000) over an alleged assault of a former partner.
The sixth seed contested the fines, forcing the case to trial.
Zverev was bemused when the only English-language question in Thursday's post-match press conference centred on whether he planned to attend the trial in person.
"Wow. That's a question," he replied.
"I just played four hours, 40 minutes ... I've got no idea."
In other men's results, Danish eighth seed Holger Rune was shocked in his second round with French wildcard Arthur Cazaux, losing 7-6 (7-4) 6-4 4-6 6-3.
Spanish No.23 seed Alejandro Davidovich Fokina was punted by Portugal's Nuno Borges 7-6 (9-7) 6-3 6-3, who will next face Grigor Dimitrov with the Bulgarian 13th seed downing Australian Thanasi Kokkinakis 6-3 6-2 4-6 6-4..
Serb Miomir Kecmanovic sent big-serving German No.24 seed Jan-Lennard Struff packing 6-4 1-6 7-6 (7-5) 1-6 7-6 (11-9).
Kecmanovic's reward is a date with last year's Open semi-finalist Tommy Paul after the American 14th seed beat Brit Jack Draper 6-2 3-6 6-3 7-5.
Elsewhere, Australian Max Purcell pushed No.11 seed Casper Ruud all the way in a gallant 6-3 6-7 (5-7) 6-3 3-6 7-6 (10-7) loss.
Ruud will next face top-ranked Brit Cameron Norrie, who turned the tables on Italian Giulio Zeppieri after falling two sets behind to win 3-6 6-7 (4-7) 6-2 6-4 6-4.
Dutch 28th seed Tallon Griekspoor was a 3-6 6-1 7-5 6-4 winner over Frenchman Arthur Fils, and French No.21 seed Ugo Humbert held off China's Zhizhen Zhang 6-2 5-7 6-1 7-6 (7-3).
