After all, the Florida great owns the Surf Ranch that will host the next leg of the Championship Tour he's no longer guaranteed a spot on.

Slater's dramatic third-round loss to Australian Liam O'Brien at the Margaret River Pro on Saturday ended hopes of a surge from 26th into the top 22 who continue beyond the tour's fifth stop.

World No.21 O'Brien, fighting for his own survival, put the heat on Slater by producing a two-wave total of 15.53.

Slater clawed his way back into the contest with a 7.83 ride, and it left him needing a 7.70 to progress.

The 51-year-old took off with 30 seconds remaining in his heat and put together a solid three-manoeuvre ride that had the commentators pondering whether it would be enough.

The judging panel gave Slater a score of 5.77, officially ending his hopes of making the cut by a solitary heat win.

But it might not be the end of Slater on the WSL main tour - and it's not even necessarily the end of his title hopes for this year.

With two wildcards on offer for each remaining event, Slater has a window to compete and, unlike last year, accumulate points for those results.

If he is handed regular wildcards he could still amass enough points to surge into the top five and vie for another world title at the end-of-season finals.

And it just so happens he owns the Californian wave park that will host the next event.

"Oh, is that Surf Ranch," Slater grinned on the WSL broadcast after bowing out.

"Yeah we'll see. I know a guy, you know. We'll see."

Slater has battled injuries since a momentous win at Pipeline last year just days before his 50th birthday.

He can also win back his spot on the main tour for next year by either finishing in the top 10 of the second-tier Challenger Series, or receiving a main tour wildcard.

"Plans for my future? I want to get really barrelled somewhere," he said of his next move.

"I don't know; I'll figure it out. Let's see how things turn out."

O'Brien thought Slater's last wave might have been enough to beat him.

"You could hear the whole beach erupt when he finished it off. Luckily I sneaked through," he said.

Earlier, Australian Callum Robson survived the cut at the expense of compatriot Jackson Baker.

Robson will next take on world No.1 Joao Chianca for a spot in the quarter-finals while Ethan Ewing has to find a way past high-flying Brazilian Italo Ferreira.

Ferreira scored a 9.03 when he soared and landed a mid-air 360-degree turn, holding the pose for good measure.

The women's round of 16 began later on Saturday, No.1-ranked Molly Picklum beating Courtney Conlogue to set up an all-Australian quarter-final with Bronte Macaulay.

Sophie McCulloch was knocked out by Carissa Moore while Stephanie Gilmore and Tyler Wright are yet to surf in their separate heats.

Australian Associated Press