MELBOURNE: Novak Djokovic and Coco Gauff were both made to toil for semi-final places on a blazing Tuesday at the Australian Open but organisers were spared a ridiculously late finish as Aryna Sabalenka and Jannik Sinner roared through the night session.

Two epic battles in the afternoon meant defending women`s champion Sabalenka did not walk onto Rod Laver Arena until well after 9 p.m. but the Belarusian made light of Czech Barbora Krejcikova, winning 6-2, 6-3 to ease pressure on the schedule.

Fourth seed Sinner then beat fifth seed Andrey Rublev 6-4, 7-6 (7/5), 6-3 just before 1.30am to set up a mouthwatering clash with Djokovic and leave a shattered Rublev picking over a 10th defeat in 10 Grand Slam quarter-finals.

Holder Djokovic was expected to breeze past Taylor Fritz having come into the contest with an 8-0 win-loss record over the 12th seeded American but he endured a stern test that lasted four hours to prevail 7-6 (7/3), 4-6, 6-2, 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 worldnumber 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.

Fritz, who at 26 is a decade younger than his opponent, made the Serb sweat in a tight first set that the American dropped in a tiebreak before drawing level in the contest on a steamy day where both players looked physically drained at times.

`I played a really high level for the first two sets and they were physically tough. It was like 2-1/2 hours by the time we finished the two sets,` said Fritz. `I need to get to the point where I can do that for five hours.

Sinnerhasbeen clinicalinMelbourne 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-matchunbeaten 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, Sabalenka was off court in just 71 minutes, crushing ninth seed Krejcikova with minimum fuss.

She will face fourth seed 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 ten-nis, 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.-Agencies