The second seed was in imperious form to start and finish on John Cain Arena, racing past the 14th seed 6-1, 2-6, 6-3, 6-2 after briefly letting his guard down.

He will meet dangerous 12th seed Paul for a place in the last four after the American whipped Spain's Alejandro Davidovich Fokina for the loss of just three games.

Zverev and Paul have played twice before, but not since Indian Wells in 2022, with the American winning both times.

"He's an incredible top player and has improved tremendously and I'm happy to be in the quarter-finals," said Zverev, a two-time Grand Slam finalist.

"Extremely happy to be in the quarters only losing one set. I definitely want to play three more matches here."

The 27-year-old has been in ominous form, building on a stellar 2024 that propelled him to a career-high two in the world.

It is his second straight run to the last eight in Melbourne, progressing to the semis last year where he lost to Daniil Medvedev.

While Zverev has made Grand Slam quarter-finals 14 times, he has never been able to go all the way after a decade of trying.

Should he finally snap the drought, he would be the first German man to win a Slam since Boris Becker in Melbourne in 1996.

He was calm and composed against Humbert, who has failed to reach a Grand Slam quarter-final in 25 attempts, despite losing the second set

After breaking the Frenchman's opening service game he kept his foot to the floor to take the first set in just 27 minutes.

But Humbert rallied to take the next set after Zverev's serve faltered and too many unforced errors crept in.

But the German refocused to reassert control, winning 100 percent of his first serve points in set three, and never surrendered.

Paul should pose a tougher assignment.

The opening Grand Slam of the year has been by far his most successful during his career, with a 15-5 win-loss record in his six tournaments.

His best Slam result came in Melbourne when he powered to the semi-finals in 2023 -- the first American man to do so since Andy Roddick in 2009.

He beat Davidovich Fokina along the way that year too before being ousted by Novak Djokovic.

"I'm always happy to be back in Australia and to be in the quarter-finals again. It's amazing," said Paul after the 6-1, 6-1, 6-1 demolition job.

"This court is where I came through to my first quarter-final ever, and now my second one here in Australia on this court.

"So great memories on this court," added the 27-year-old, who dominated on serve against the Spaniard while crunching 25 winners.