Heavyweights Carlos Alcaraz and Novak Djokovic have taken vastly different paths to the Australian Open third round.

World No.3 Alcaraz laid down a marker with a strong serving display in his 6-0 6-1 6-4 demolition of Japanese opponent Yoshihito Nishioka on Wednesday.

Ten-time Open champion Djokovic had to claw his way past 21-year-old Portuguese qualifier Jaime Faria, overcoming his own frustration on the way to a hard-fought 6-1 6-7 (7-4) 6-3 6-2 victory.

"I think I responded very well in the third and particularly fourth set, the way I ended up the match," Djokovic said.

"He (Faria) was playing lights-out tennis. It was the end of the second set and beginning of the third, I had to weather the storm.

"He's been practically serving two first serves the entire match. It's not easy to play someone like that who obviously doesn't have anything to lose in coming out.

"He's a big guy, very young I think 20 or 21 years old, so I told him at the net the future is bright for him and he should keep it going."

Alcaraz's win kept the four-time major winner on track as he chases his first success at Melbourne Park and seeks to become the youngest player to complete a career grand slam.

The 21-year-old Spanish star will next face a third-round clash with Portugal's Nuno Borges, who ousted local hope Jordan Thompson in straight sets.

After tweaking his service action over the off-season, in search of more rhythm and precision, Alcaraz landed 60 per cent of first serves and sent down 14 aces to Nishioka's one.

It was the third-highest number of aces Alcaraz has delivered in a match on tour, in an ominous sign for his Open rivals.

"I'm really happy with the serve today. It's something that I worked (on) in the pre-season," Alcaraz said in his on-court interview.

"In the first round I struggled a little bit, so I wasn't too happy in the first round with the serve.

"Today I was more focused and on practising the serve I spent more time serving with Juan Carlos (Ferrero) and my team.

"It's something that I really want to be better, so I'm just glad that today it worked pretty well.

"Hopefully in the next round it's going to be better."

With the match seemingly headed in one direction during the second set, Nishioka played up to the crowd when he willed an Alcaraz shot to drift long.

It did, handing the smiling world No.65 his first game of the match as fans roared their approval.

Nishioka, who achieved career-best grand slam results with fourth-round appearances in Melbourne and Paris in 2023, took another four games on serve during third set.

But he lacked the ammunition to seriously trouble Alcaraz and was thoroughly outclassed.

Djokovic, who could meet Alcaraz in a quarter-final, next faces Tomas Machac after the Czech 26th seed outlasted Reilly Opelka in a five-set slugfest, 3-6 7-6 (7-1) 6-7 (5-7) 7-6 (7-4) 6-4.

Jiri Lehecka also moved into the third round when French opponent Hugo Gaston retired with the Czech 24th seed leading 6-3 3-1.