Italy's fourth seed trounced young Dutch qualifier Jesper de Jong 6-2 6-2 6-2 in one hour and 43 minutes on Wednesday to enhance his status as a huge threat to 10-time champion Djokovic.
Sinner beat the world No.1 twice in the space of a week in December and is continuing his hot run in Melbourne.
The world No.4 broke de Jong six times while powering into a third-round meeting with 26th seed Sebastian Baez on Friday.
"It doesn't really matter who you play against: you fear nobody, but have a lot of respect for everyone," the 22-year-old Sinner said.
"This is what I try to show to everyone."
Heavy rain in Melbourne forced the match to be played under a closed roof at Margaret Court Arena.
Jannik Sinner signs autographs for fans after his straight-sets win in the second round. (Lukas Coch/AAP PHOTOS)
Sinner, who enjoyed a stellar indoor season in 2023, was perfectly satisfied with that.
"For me, they can play the whole tournament indoors," he said.
In a battle of South Americans for the right to face Sinner, diminutive Argentine Baez overcame crafty Colombian Daniel Elahi Galan 7-5 2-6 6-2 6-4 in three hours and 14 minutes.
Baez, a former junior world No.1, won a career-best three ATP Tour titles in 2023 and equalled his best performance at a grand slam with Wednesday's victory.
Australian 10th seed Alex de Minaur also advanced with a straight-sets win over Italian Matteo Arnaldi.
The local hope will face another Italian for a spot in the last 16 after qualifier Flavio Cobolli knocked off Russian Pavel Kotov 7-5 6-3 5-7 6-2.
Taylor Fritz needed less than 90 minutes to win his second-round match at the Australian Open. (AP PHOTO)
Taylor Fritz continued the searing run of form by the men's seeds at Melbourne Park, slamming down 11 aces and 38 winners in his 6-0 6-3 6-1 belting of French qualifying lucky loser Hugo Gaston.
The powerful American was on Kia Arena for less than 90 minutes after surviving a five-set scare against Facundo Diaz Acosta in the first round.
"After that long one in the first round, it's great to get some time back," Fritz said.
"Because as you progress through the draw, you really want to keep the time down on court as much as possible."
Fritz will face either Argentine 22nd seed Francisco Cerundolo or Hungarian Fabian Marozsan in the third round.
The 12th seed had never been past the round of 32 of a major until the 2022 Australian Open, when he won a five-set thriller over Roberto Bautista Agut.
Despite his recent run of success, rising to world No.5 and reaching two grand slam quarter-finals, Fritz insists his mindset for majors remains unchanged.
"I approach it the same ... one match at a time," he said.
"It was a really special moment for me on this court (in 2022) against a guy that had up until that point in my career owned me (Frances Tiafoe). It was huge.
"So it was great to be back on this court, and hopefully I keep getting put back on here because it's working for me."
Later on Wednesday, Djokovic faces Australia's Alexei Popyrin in the feature night match at Rod Laver Arena.
Other big guns in day-four action include seventh-seeded 2023 Open runner-up Stefanos Tsitsipas against another local, Jordan Thompson, and Russian fifth seed Andrey Rublev against American Chris Eubanks.
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