Australian wildcard George Pittar continued his stunning run and Brazilian Samuel Pupo was left in tears on a shortened but drama-filled day at the Margaret River Pro.

Only four heats were surfed on Friday in the men's round of 16 due to fading conditions at the World Surf League (WSL) event in Western Australia.

Pittar, competing in just his second WSL event, provided the feel-good story when the 21-year-old defeated countryman Liam O'Brien in the final heat of the day to book a quarterfinal berth.

"Far out, I can't even believe what's going on," Pittar told the WSL broadcast.

"It's easier coming into this event with less pressure. Everyone's having to worry about the cut, and there's so much on the line.

"For me, I'm padding out there and it's all experience for me.

"It's pretty crazy I'm in the quarterfinals. I'm tripping."

The most emotional moment of the day belonged to 23-year-old Pupo, who was left in tears after beating his older brother Miguel Pupo in a result that ensured his 32-year-old sibling missed the mid-season cut.

"To get him off tour, I just feel like a loss really for me," Samuel said while wiping away tears.

"Without him, I wouldn't be anywhere near where I am now. Maybe I wouldn't be surfing.

"For me to be in this position is all because of him.

"But he's really strong, I'm sure he's going to come back.

"He just got out of the water smiling, and he looked like he was the one that won the heat.