Defending champion Jack Robinson has become a shock Pipe Pro casualty, but Ethan Ewing emerged as the lone Australian male standing after the season-opening event in Hawaii resumed.
West Australian pipe specialist Robinson was taken out in the round of 32 by Morocco's Ramzi Boukhiam in a tight clash, with last season's tour runner-up Ewing moving into the quarter-finals for the first time.
Boukhiam only got a start at Banzai Pipeline as a replacement for injured Brazilian Joao Chianca, but showed no fear against the world No.5.
He managed just two scoring waves for a total of 10.83, but it was enough to pip new father Robinson, who tallied 10.16.
Queensland's second-ranked Ewing got the better of all-time great Kelly Slater before accounting for fellow Australian Liam O'Brien - 14.83 to 12.00 - in the round of 16 thanks to a pair of seven-point rides.
Ewing earlier caught Slater napping, recording a 7.83 despite not having priority at the time.
His two-wave total of 12.66 was well clear of the 11-time world champion's 4.27, despite the American catching 10 waves.
"It's always nerve-wracking but also exciting coming up against Kelly," Ewing said.
"He's always been one of my favourite surfers and probably the greatest surfer to surf this wave.
"This wave is so challenging and has so many different faces, I'm just trying to learn as much as I can."
Ewing will face Connor O'Leary in the quarters, the Cronulla-raised O'Leary now surfing for Japan where his former surf champion mother was born.
Callum Robson dropped a 9.33-point total - the event's highest-scoring wave - when he found a deep barrel in the final four minutes to beat Hawaii's Seth Moniz and reach the last 16.
But he ran into red-hot John John Florence, Robson (5.00) only scoring on three waves as the local hope (11.83) ensured Ewing would be the last Australian standing.
"Those heats are the ones I'm always happy to make it through because there's just not a lot of waves coming through and it's hard to have that kind of battle you want to have," Florence said.
"Earlier, Callum got that nine right after I had my heat and he's so scary in these conditions. All I can think about was that I'm going to need a better wave."
The women are yet to hit the water, with surfing having only been possible on two days since the window opened on January 29.
