An afternoon of carnage at the Rip Curl Pro left a succession of broken boards and top surfers counting their blessings.

It is nicknamed "victory at sea" - surfing in stormy conditions.

Florence and defending event champion Italo Ferreira had near misses when the powerful three metre-plus surf washed them close to the rocks.

Australian Owen Wright also had his board broken during an epic round-of-16 heat with Florence.

The forecast of some of the biggest surf in event history drew a big crowd and the conditions did not disappoint.

The surf built throughout the day and, by the end of the men's last-16 heats, wipeouts were commonplace.

It said something about Friday that Florence was taken aback, given he learned his craft in Hawaii's unforgiving North Shore surf.

"It's big in there, so it's really scary, kicking out next to that (rock) shelf at Winkipop," the two-time world champion said.

"I saw it coming, I just felt all the water pulling me towards there and I thought 'oh my gosh, this is bad'."

Wright said he certainly took notice when he ducked under a wave and his board snapped in two.

"That was when you thought 'whoa, this has gone up a level'," the Australian said.

"It wasn't scary as such, more like 'pay attention - be alert, don't just duck dive these white washes thinking you're going to get off free'.

"It definitely demanded your attention out there."

Florence and Wright had a pulsating heat, with the Hawaiian's 9.63 the highest wave score of the day.

He came from behind to win 18.16 to 16.97 and set up a headline quarter-final on Saturday against Brazilian reigning world champion Gabriel Medina.

Between them, Medina and Florence have won the past three worlds titles - but they are yet to ring the famous Bells Beach trophy.

Trials winner Jacob Willcox and Ryan Callinan have made the Rip Curl Pro quarters for the first time and they are the last Australians still in the men's or women's draws.

Ferreira's quarter-final against South African Jordy Smith will also be one to watch, given they are the past two Bells Beach winners.

Amid speculation this is his last competition at Bells Beach, 11-time world champion Kelly Slater is also through and will face Callinan in the last eight.

The men's and women's titles will be decided on Saturday, with conditions forecast to remain solid.

Australian Associated Press