Sabalenka is the defending champion, having landed her first Grand Slam crown at Melbourne Park last year, and is yet to drop a set in her run to the semis this season.
She is only the third woman to reach six consecutive Grand Slam semi-finals since the turn of the century after Americans Jennifer Capriati and Serena Williams.
The Belarusian baseliner was once famous for failing to master her emotions on court but the Sabalenka who has demolished all comers in Melbourne this year seems far more at ease with herself.
Her social media feeds are filled with lighthearted moments with her coaching team, and one of her rituals is to sign her name on her fitness trainer's bald head before each match.
Levity aside, however, she remains a formidable competitor, with the raw power to blow her opponents away from the back of the court.
"After the US Open, I really want that revenge," Sabalenka said of her meeting with Gauff.
Teenager Gauff, who won her first Grand Slam title at the US Open, leads their head-to-head with four wins from six meetings and knows she will have to raise her game if she is to reach the final.
She eased into the quarters without dropping a set but her level dropped noticeably in her last-eight clash with Marta Kostyuk.
She struggled with her serve against the Ukrainian and was forced to fight her way back from 5-1 down in the first set, then lost a second set tiebreak, before finally finding her feet in the third set to advance.
"Definitely a 'C' game," was Gauff's verdict. "Didn't play my best tennis."
A lot will depend on whether Gauff can get her service game back to where it was before the quarter-final.
While the second semi-final could have been forecast before the tournament, it would have been a brave pundit who would have predicted the first between Dayana Yastremska and Zheng Qinwen.
The pair came through the top half of the draw where all but one of the 16 seeds were knocked out before the quarter-finals, including world number one Iga Swiatek.
NO REGARD TO RANKINGS
Ukrainian Yastremska, who will be playing her ninth match at the tournament after becoming the first women's qualifier to reach the last four in Melbourne since 1978, said she had been paying no regard to rankings.
"The girls at any ranking can show amazing game," she said. "I was doing just my thing and focusing on myself, the way I play. I think that's working."
Zheng, the 12th seed, is looking to follow in the footsteps of compatriot and hero Li Na, who became the first Chinese player to win the Australian Open a decade ago.
Li, who played four semi-finals in Melbourne, gave the 21-year-old some advice when they met after Zheng's third-round victory.
"She said to me 'don't think too much, just keep it simple'," Zheng said.
