Slater of the United States was hit with an interference penalty 2 call during the first wave of his round-of-32 heat against South Africa’s Matthew McGillvray.

As Florence committed to a ride in the dying moments of the Hawaiian’s heat against US rookie Jake Marshall, Slater passed the competitor and surfed, making a clean exit at the back of the wave.

The problem lied with Florence having priority during the overlapping heats, and Slater was slapped with a costly penalty.

In the end, Slater scored 2.5 whilst McGillivray reached a commanding 15.67.

"John and Jake caught waves and they were in," 50-year-old Slater told the WSL broadcast.

"And I thought 'Okay, I’m kind of free, I’m on the peak, I can get a wave'.

"I caught it, and then I saw John paddling down the line.

"I thought, 'he’s pretty far down the line and I’m already riding'.

"By the time I had committed to my bottom turn, I was like 'Oh shoot, I’m under John’s line'.

"He wasn’t technically up and riding yet when he crossed my line.

"I don’t think that I affected John’s wave in any way. 

"I don’t think he got up until he passed me.

"But the rule is the rule, and we have to play by them."

Regarding his dislike for Sunset Beach, he added: "I don’t respect the wave and it doesn’t respect me back."

Florence followed the world number one out of the competition as his score of 13.27 was not enough to beat Marshall's 13.93.

The round of 16 saw Australia’s Ethan Ewing beat Brazil’s Filipe Toledo after scoring 9.67, and compatriot Jack Robinson overcoming McGillivray.

Conner Coffin of the US and Brazil's Italo Ferreira - the Olympic champion - also lost in the third round.

Of the remaining eight surfers, Hawaii’s Seth Moniz sits second on the season leaderboard, in front of Brazil’s Caio Ibelli in third and Japan's Kanoa Igarashi in fifth.

Young Hawaiian wildcard Barron Mamiya is in ninth.