The 23-year-old Sunshine Coast talent showed no fear against the seven-time world champion, pairing a 6.67-point wave with a 7.23 effort, the second pinched from under Gilmore's nose when she passed it up.

The result is Nichols' best on the Championship Tour while Gilmore's defeat follows the earlier exits of fellow highly-fancied Australians Tyler Wright and Sally Fitzgibbons.

It's a blow to Gilmore's hunt for an eighth world title after her exit at the same stage in the season opener in Hawaii last December.

Not that Nichols will care, the 23-year-old showing skill to first establish the lead then composure to hold her nerve in the final minutes while holding priority from a desperate Gilmore.

"Steph is my idol, she always has been and always will be," Nichols told Fox Sports.

"I told her that after the heat.

"She was the first person I looked up to and I still do. So to have a heat against her was really surreal.

"I'm pretty stoked. I didn't think that was how that heat was going to go, but I'll take it."

Nichols will now face fellow Australian Keely Andrew, who pulled off an upset by beating American Courtney Conlogue 13.7 to 12.9.

West Australian Bronte Macaulay couldn't join her peers in the semi-finals, beaten 16.26 to 12.97 by Caroline Marks.

Four-time world champion Carissa Moore shocked even herself when she pulled off a stunning aerial in her quarter-final victory over France's Johanne Defay.

Moore earned a near-perfect 9.9 wave score when she shot into the air and landed the 360-degree twist in one of the best aerials ever seen on the women's tour.

"I just felt really good. I never really land those things, especially in a heat," Moore said.

Moore, who beat Defay 17.33 to 14.1, will face off against Marks in the semis.

Newcastle hasn't hosted a Championship Tour event since 1993, with action returning to the NSW city after the coronavirus pandemic led to the cancellation of regular stops on the Gold Coast and Bells Beach.

Australian Associated Press