The second seed -- seen as the biggest threat to defending champion Novak Djokovic -- did not face a single break point in a dominant performance, rolling over his opponent 6-4, 6-4, 6-0 in one hour 49 minutes.
The Spaniard, who chose not to play any competitive tennis in the build-up to the first Grand Slam of the year, said he "did everything perfectly".
"I pushed him to the limit in every ball, every point," he said. "He has played a lot of tough matches before this one, so probably physically he wasn't 100 percent.
"I could take my chances in every set and it was a pretty good match for myself.
"I'm feeling better and better every day. Every match I play here on Rod Laver (Arena) I feel more comfortable. Pleasure to play here, amazing court."
Making his first appearance in the last 16 at Melbourne Park, the 20-year-old was quickly into his stride, breaking in the third game.
The second set went with serve until the seventh game, when Alcaraz broke again, which proved enough for a two-set lead.
The third set became a procession as the Spaniard stepped up a gear -- a deft drop shot set up match point and a thunderous serve sealed the deal.
Alcaraz has yet to be fully tested but has shown glimpses of his best form in Melbourne.
In Monday's match he won 83 percent of first-serve points, took advantage of five of his nine break points and hammered 43 winners.
The Australian Open is doubling up as a shootout for the number one spot and defending champion Djokovic has already laid down a marker, dropping just three games in his fourth-round match on Sunday.
