Australian Jack Robinson has defeated surfing's GOAT with Kelly Slater's late comeback falling short in their Tahiti Pro showdown at Teahupo'o.

Eleven-time world champion Slater wound back the clock with a stunning second-round upset over star Brazilian Gabriel Medina earlier in the week, but the 54-year-old wildcard knew he would have to produce more magic to defeat Robinson on Thursday.

Things looked grim for Slater when he lost priority and watched on as Robinson snared a 9.17-point barrel ride to "combo" his American rival, having already secured a 5.83 earlier in the heat.

It meant Slater needed two big scores and he got himself back in the contest with just minutes to go with a 7.83 ride.

The surfing great then lured Robinson into using up his priority on a smaller wave, but Slater couldn't paddle back out in time to catch the next big set rolling through with his efforts to duck-dive and reach the launching spot all in vain as the clock wound down.

"I had fun," Slater said.

"I took a bad one with my first priority and then Jack had his nine, so I was on the back foot.

"I got myself back in there luckily. With three minutes to go I got that quick one. 

"I had to paddle in and force Jack to take a small one, but then I couldn't get back out for that set. It just never felt like I was in sync. I think I used all my magic up the last two heats."

Slater, who retired from full-time surfing in 2024, has his fingers crossed the WSL will hand him another wildcard for the season-ending Pipeline in December. 

"If they give me Pipe, I'll surf that for the rest of my life. I've got to start lobbying," Slater said.

Robinson was thrilled to get the win against Slater.

"Little Jack remembers the first heat he surfed against Kelly," Robinson said.

"I was 13 at Keramas (in Bali). I've got the utmost respect for Kelly. I was able to get the job done today."

Robinson will next face American Griffin Colapinto in the quarter-finals, with the competition expected to conclude on Friday (EST).

Fellow Australian George Pittar also made the final eight after defeating Brazilian Alejo Muniz 13.66 to 2.10.

Ethan Ewing will take on current world No.1 Italo Ferreira in the quarter-finals after defeating Liam O'Brien in their round-of-16 match-up.

In the women's draw, Australians Molly Picklum and Isabella Nichols made it through to the quarter-finals, but five-time world champion Carissa Moore was knocked out by Canadian Erin Brooks.

Fourteen-year-old wildcard Kelia Gallina continued her giant-killing run by taking down American Caroline Marks just a day after defeating Tyler Wright.