Top seed Novak Djokovic battled into an 11th Australian Open semi-final and a record-extending 48th at Grand Slams on Tuesday, but a rampant Aryna Sabalenka had a much easier ride.
The Serbian superstar came through a probing test on Rod Laver Arena against 12th-seeded American Taylor Fritz 7-6 (7/3), 4-6, 6-2, 6-3 to keep his bid for an unprecedented 25th major crown on track.
He will meet in-form Italian fourth seed Jannik Sinner, who swept past Russian fifth seed Andrey Rublev 6-4, 7-6 (7/5), 6-3.
Djokovic almost always gets the evening slot on centre court, but was bumped to the afternoon on a day on which temperatures soared to 32 degrees Celsius (90 degrees Fahrenheit) and the world No one admitted it was tough going.
"Physically and emotionally very draining," he said after the three hour and 45 minute epic, adding that he "suffered a lot" in the first two sets.
"He was serving well, staying close to the line and kind of suffocating me from the back of the court," he said.
"I think I upped my game probably midway through the third set all the way to the end."
Sinner has been clinical in Melbourne and is yet to drop a set. He also beat Djokovic at the Davis Cup late last year, but the omens are not good for him.
The 36-year-old has won all 10 previous semi-finals he has played at the Australian Open, stretching back to his first title in 2008 and is on a 33-match unbeaten streak on the blue hardcourts.
"I'm lucky to face him at one of the biggest tournaments in the world," said Sinner.
"It's going to be tough. The only thing I can control is that I am going to give 100 percent and I will fight for every ball."
In contrast to Djokovic's long slog, fellow defending champion Sabalenka was off court in just 71 minutes, crushing ninth seed Barbora Krejcikova 6-2, 6-3 with minimum fuss.
She will face fourth seed Coco Gauff next in a replay of last year's US Open final that the American teenager won in three sets.
On current form, Gauff will be the underdog after taking more than three hours to down unseeded Ukrainian Marta Kostyuk 7-6 (8/6), 6-7 (3/7), 6-2 in a scrappy affair.
"I love it, I love it. After the US Open, I really wanted that revenge, and, I mean, that's a great match," Sabalenka said of her semi-final.
Sabalenka had won all seven of her previous Grand Slam quarter-finals, and wasted little time laying down the law against Krejcikova, the 2021 French Open champion.
She broke three times in each set, with her booming groundstrokes unstoppable.
"I played really great tennis, I just hope I can keep playing this way," said the 25-year-old.
Gauff admitted she was below par against Kostyuk, giving herself only a 'C' rating.
"Hopefully got the bad match out of the way and I can play even better," she said.
"Really proud of the fight I showed today," added the American, who had never progressed beyond the fourth round at Melbourne Park in four previous attempts.
The low standard was not confined to Gauff, with the pair making a staggering 107 unforced errors between them – there were 16 service breaks.
Kostyuk rued missing her chances, letting slip a 5-1 lead and squandering set points in the first set, but said she was proud of how she fought.
"Very proud of myself. I won for myself today, and I think it's the most important thing," said the 21-year-old, who has been vocal at the tournament about keeping people's focus on the conflict in her homeland.
The victory extended Gauff's winning streak this year to 10 matches after she lifted the title at Auckland in the lead-up, and her unbeaten run at Grand Slams to 12 after her exploits at Flushing Meadows.