The 21-year-old third seed dropped a set but was a class above Portugal's Nuno Borges on Rod Laver Arena, dumping him out 6-2, 6-4, 6-7 (3/7), 6-2.

It was the Spaniard's first time on centre court this year after being shunted to neighbouring Margaret Court Arena for his opening two matches.

With the sun shining, he revelled in the atmosphere, rattling off 54 winners and nine aces, dominating from the baseline.

"The last time I played here I lost, I really wanted to play here and get another win on Rod Laver," said Alcaraz, a four-time Grand Slam winner who is gunning for a first title in Australia.

"It's a privilege to feel the love here in Australia. I'm trying to play different tennis, that's what makes me enjoy playing tennis, what makes me smile on court.

"And to entertain the people as well, making them happy."

He will face either Briton Jack Draper or Australia's Aleksandar Vukic next.

Alcaraz is bidding to become the youngest man to complete a career Grand Slam -- winning all four majors -- in the Open Era.

His compatriot Rafael Nadal did it in 2010 aged 24.

Should he achieve the feat, he will also rewrite the record books as the youngest champion at Melbourne Park since Novak Djokovic in 2008.

To do so he will likely have to beat the Serbian star, who he is seeded to meet in a blockbuster quarter-final.

Alcaraz, who is sporting a new buzz cut in Melbourne, already has eyes on the trophy and vowed to get a kangaroo tattoo if he goes all the way.

"It's a kangaroo, that's for sure. That's my idea," he said.

"The only thing I miss is to lift the trophy here, but the plan (for a tattoo) is already taken."

When Alcaraz won the US Open he got inked with the date of his achievement and followed up by getting tattoos of the Eiffel Tower and a strawberry when he won the French Open and Wimbledon.

Fired-up 

Alcaraz started strongly against Borges, earning an immediate break with the Portuguese player netting a backhand under pressure.

Borges, who won a maiden ATP title last season, beating the now-retired Nadal, had no answer to Alcaraz's powerful groundstrokes and was broken again in game seven on his way to losing the set.

The 27-year-old gamely clung on in the second set to 4-4 when the Spanish star slammed a forehand winner for the break and served out with his fifth ace of the day to snare a two-set lead.

Borges was on the defence in set three, fighting off two break points from Alcaraz in an enthralling 16-point seventh game to keep the set on serve.

Borges refused to lie down and it went to a tie break where he stunned the world number three by winning it emphatically.

Alcaraz was riled up and after holding serve to love to open the fourth set, he produced a magical forehand winner for a break and sprinted to the finish.