Alcaraz faces Chinese young gun, Swiatek aims to extend hot streak
The Spanish world number two blitzed Richard Gasquet in his opener in Melbourne and came through his second-round match against Italy's Lorenzo Sonego in four sets.
He is aiming to become the third man in the Open Era to win three Grand Slams before the age of 21, after Bjorn Borg and Mats Wilander.
He also has the chance to supplant Novak Djokovic as world number one.
Shang, 18, is an unknown quantity for the two-time major winner, who is in the unusual position of facing someone younger than himself.
"I've never practised with him, I've never played against him, so it's going to be the first time that we face each other," said the 20-year-old Wimbledon champion.
"What I've seen so far from him, he's an unbelievable player. He's ready to make a good result. I have to be focused on that, and I will prepare as best as I can."
Top women's seed Swiatek is the player in form on paper, currently on an 18-match winning run, but she had to dig deep to see off former finalist Danielle Collins in the second round.
On her days off she has witnessed defending champion Aryna Sabalenka pummel her three opponents into submission, for the loss of just six games in total.
The 22-year-old will be keen for a big win of her own against unseeded Czech Linda Noskova to confirm that she is the player to beat as she hunts a fifth Grand Slam title.
Swiatek, who faced former Australian Open champion Sofia Kenin in the first round, said her draw was "like the toughest one I ever had".
But she believes she could benefit from her baptism of fire in Melbourne.
"I don't mind actually that it was intense because I remember also when I started the tournament with some easy matches, then I felt I was a little bit rusty when the tough moments came," she said.
Men's third seed Daniil Medvedev is back on court after his gruelling five-set encounter with Finland's Emil Ruusuvuori, which finished at 3:40 am on Friday.
The Russian, a two-time finalist in Melbourne, faces a potentially tough assignment against Canadian 27th seed Felix Auger-Aliassime, while sixth seed Alexander Zverev takes on unseeded American Alex Michelsen.
Many of the top women's seeds have fallen but 11th seed Jelena Ostapenko, a quarter-finalist last year, remains alive and will face two-time champion Victoria Azarenka.
