Aussie Paris Olympics surf star Jack Robinson reveals he almost DROWNED before being rescued from the 'most dangerous place in the world'

Australian Jack Robinson has revealed he almost drowned in treacherous conditions while sending world No.1 John John Florence home from the Olympic surfing competition with a stunning win.

In deteriorating conditions which forced the women's heats to be abandoned on Tuesday (AEST), Ethan Ewing also advanced, setting up an all-Aussie quarter-final.

A storm system south of French Polynesia, hosting surfing for this year's Olympics, made for terrifying action in Teahupo'o.

The wildness elevated the blockbuster Robinson-Florence heat between the World Surf League's number one and three ranked surfers.

In noticeably bigger surf than previous days, neither were able to put a meaningful score on the board in the first half of their 30-minute heat.

Chasing a wave, Robinson and Florence both disappeared into the wash and required rescuing from jetskis within seconds of each other.

Returning to the fray after being towed through the lagoon and back past the Pacific Ocean waves, Robinson recovered best.

The 26-year-old stood tall after dicing with the reef, plunging into a barrel to score 7.17 in a decisive ride.

A second score took the Western Australian out of reach of Florence, the two-time world champion, eventually winning 13.94 against the Hawaiian's 9.07.

'I got dragged over the bottom and almost had a two wave hold under,' Robinson said.

'I didn't get much air. There wasn't much time. I got reminded of so many guys who have had so many bad wipe-outs here.

'I have had some pretty bad (wipe-outs) but in a contest it's different. You have way more adrenaline and there is way more on the line.

'(Paddling back out was) a test of physicality and spirit.'

Robinson stressed just how dangerous his sport can be.

'Every other sport is in a court or a stadium,' he said.

'We are in an ocean. It is the biggest, most powerful source of life we have on this planet.

'The waves are so powerful. It doesn't relate to any other sport. Maybe an avalanche coming down on your head on a mountain. Maybe it's similar to that. It's so dangerous and so crazy.'

Florence said he was flummoxed by the draw that allowed two of the world's top three in-form surfers to meet so early in the tournament.

'It sucks to come up against Jack this early on. One of us had to win and one of us had to lose. It's hard,' he said.

The result was a repeat of the Robinson's win from April's Margaret River Pro final.

Shortly after Robinson's progression, Ewing joined him in the last eight by defeating Australian-born Connor O'Leary, representing Japan.

Their heat resembled a battle to survive in the barrels, with both men taking all manner of tumbles, including one cringe-inducing face plant by O'Leary.

'I had some wipeouts but stoked it paid off ... I have so much water in my head right now. It feels good to be back on the land now,' Ewing said.

Wave selection was paramount and Ewing did best: scoring an 8.67 with a deep run to defeat O'Leary 14.17 to 11.00.

The All-Aussie quarter-final means both men cannot medal in the surfing but at least one will play off in the last four.

'It'll be cool,' Ewing said of the match-up.

'He (Robinson) is definitely pushing the limits and one of the best guys out here, and that's where I want to be. So it will be exciting for sure.'

Earlier, Joao Chianca triumphed in one of the greatest heats in the two Olympics of the sport's history, defeating Morocco's Ramzi Boukhiam 18.10 to 17.80.

Chianca's reward is an all-Brazilian quarter-final with Gabriel Medina.

There will be three quarter-finals pitting compatriots against each other, with Tahitian Kauli Vaast, representing France, against Joan Duru.

The final quarter-final will see Peru's Alonso Correa take on Brazil's Reo Inaba, who progressed with a score of just 6.00.

With the women's round three postponed and worsening conditions forecast for Wednesday (AEST), the surfing appears certain to be kicked into reserve days.