It was one heck of a 24-hour window for Nat Young at the Hurley Pro Sunset Beach in Oahu, Hawaii.

The Santa Cruz surfer was fighting to stay alive in the Elimination Round at the second Championship Tour event of the season Wednesday. He not only won that three-surfer heat, but tacked on two more heat wins in head-to-head action Thursday to advance to the quarterfinals in Oahu, Hawaii.

Young pulled off a massive upset, and eliminated two-time World Surf League champion John John Florence on his home turf in the Round of 16. Young prevailed 12.10 to 8.83. He was highly active, and attempted nine rides, and counted wave scores of 7.60 and 4.50 in the 40-minute heat, which played out in 6- to 8-foot surf.

“I definitely had a game plan of how I wanted to approach that heat with John John,” Young said. “I’m not sure how well I executed the game plan I had, but I think it kinda played into me making that heat. I felt good against him, I didn’t feel any pressure at all, but the heats before, I had some nerves. He’s the favorite out there for sure, but if I surfed my best and put up a good heat, I’d be happy.”

It was Young’s first win over Florence in five head-to-head meetings. Ninety-five percent of the fans who voted on wsl.com projected Florence would win the heat.

Florence, who won WSL titles in 2016 and ’17, finished in ninth place in Sunset Beach and earned 3,320 points for his finish.

It doesn’t get any easier for Young. He’ll square off against top-ranked Jack Robinson of Australia in Heat 1 of the quarterfinals. Robinson won the Billabong Pro Pipeline in Hawaii to open the CT season on Feb. 8.

Other quarterfinal matchups include Ethan Ewing of Australia against Griffin Colapinto of Mission Viejo in Heat 2, Filipe Toledo of Brazil against countryman Caio Ibelli in Heat 3, and Joao Chianca of Brazil against Matthew McGillivray of South Africa in Heat 4.

Ewing eliminated 11-time WSL champion Kelly Slater in the Round of 16.

Young beat Callum Robson of Australia 11.00 to 8.33 in the Round of 32 earlier Thursday, producing both of his scoring waves without priority.