After a temporary lapse of concentration midway through his first-round win over Alexander Shevchenko, Alcaraz remained dialled-in throughout his 6-0 6-1 6-4 victory at Margaret Court Arena on Wednesday.
It 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.
Carlos Alcaraz is in ominous form in the early stages of the Australian Open. (Lukas Coch/AAP PHOTOS)
The 21-year-old will next face a third-round clash with either local hope Jordan Thompson or Portugal's Nuno Borges.
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."
A Carlos Clinic.— #AusOpen (@AustralianOpen) Carlos Alcaraz defeats Nishioka 6-0 6-1 6-4 to charge into the third round!#AO2025 • @wwos • @espn • @eurosport • @wowowtennis pic.twitter.com/pgjyz6CplyJanuary 15, 2025
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.
Jiri Lehecka also moved into the third round when French opponent Hugo Gaston retired, with the Czech 24th seed leading 6-3 3-1.
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