Novak Djokovic came through a stern test against Frances Tiafoe to book his place in the third round of the Australian Open and continue his campaign for a record-extending ninth title at Melbourne Park.
The Serbian top seed looked in control after taking the first set, but lightning-quick Tiafoe, who reached the quarter-finals two years ago, refused to go quietly.
The American bounced back to take a close second set before Djokovic dug deep to emerge a 6-3, 6-7, 7-6, 6-3 winner and continue his title defence.
"Very tough match. when the sun was on the court it was very warm. A lot of long rallies," Djokovic, 33, said. "A great fight from Frances, a great match on his part.
"But it's not the first time I've been in that kind of situation, I know how to handle this type of circumstance."
He will next play another American, either Taylor Fritz or Reilly Opelka.
Djokovic, who dropped only six games in his opening round clash, had never played Tiafoe, but quickly adapted.
On a hot day, with ice towels being used for the first time at the tournament, he immediately broke to race into a 3-0 lead, but some uncharacteristically poor serving allowed the energetic American back in the set.
It was a stumble that rattled Djokovic who quickly broke again, pumping his fist in the air as he screamed at his box.
Neither player gave an inch in the tight second set, with Tiafoe's mix of power and unusual shots appearing to put Djokovic off his game as he came out on top in a tiebreak.
The Serb moved up a level in the third set, but so did Tiafoe as they traded blows until too many unforced errors ensured Djokovic took the set.
They went shot-for-shot in the fourth until a glorious backhand gave Djokovic the crucial break for 4-3, with a frustrated Tiafoe slapped with a warning for swearing then double-faulting to hand the top seed the match.
Djokovic, chasing an 18th Slam crown to close in on the 20 held by Roger Federer and Rafael Nadal, has won a record eight times in Melbourne.
It was the scene of his maiden Grand Slam triumph in 2008 and he is unbeaten on the famous blue courts since his shock defeat by South Korea's Hyeon Chung in the 2018 round of 16.
Wawrinka fightback falls short
Three-time Grand Slam champion Stan Wawrinka admitted that hesitating at a crucial time during a draining five-set cost him a chance of matching his quarter-final run last year.
The 35-year-old Swiss, the tournament winner in 2014, struggled to match the intensity of Marton Fucsovics in the opening two sets but regrouped to stay in the fight.
The 17th seed had three match points in the fifth set tiebreaker but blew them all, with the Hungarian reeling off five straight points for a famous 7-5, 6-1, 4-6, 2-6, 7-6 win in just under four hours.
"It was tough match of course, five sets, four hours," said Wawrinka, whose tournament preparations were upset when he contracted Covid-19 before Christmas.
"Always a difficult battle against my opponent, we played a few times in the past, always really tough matches and today was the same.
"It was not the best level for me, but again, I was fighting, I had some chance to finish the match, I didn't finish, I hesitated a little bit when I had the match point and I lost it."
Fucsovics, ranked No 55, last year equalled his best Grand Slam result in Melbourne when he reached the round of 16, only to be sent packing by Roger Federer.
He will now play Canadian 14th seed Milos Raonic, who beat France's Corentin Moutet over four sets, for a place in the fourth round, where Djokovic potentially awaits.
