Jamie O'Brien had one last shot in his wave-riding arsenal, and it was a big one.

As a result, he won the Da Hui Backdoor Shootout yesterday. The final two rounds of the unique contest were completed in 6- to 8-foot waves at the Banzai Pipeline.

O'Brien had the highest-scoring wave of the entire contest during yesterday's morning heats to top Kaua'i's Bruce Irons in the final standings.

"It's pretty amazing," O'Brien said. "I didn't think the waves would be that good today, but it held up. I didn't think anybody could catch Bruce, but I did."

The Backdoor Shootout featured three days of barrel riding by some of the world's best big-wave surfers. In a unique format, no surfers were eliminated. All 32 competitors were allowed to surf in six 30-minute heats staged over three days.

Ultimately, it turned into a duel between O'Brien and Irons, and they put on a show fitting for the epic conditions.

O'Brien had the lead after the first day. Irons took over during the second day.

"That was insane watching them go back and forth," said Maui's Ola Eleogram, who placed third. "Those are two of the best barrel riders out here. It was fun just to watch."

The Backdoor Shootout also used a unique scoring format. A perfect score was 40 (if the four judges each awarded a 10), but surfers could also earn bonus points for rides deemed better than perfect.

Entering yesterday's heats, O'Brien needed a better-than-perfect score of 45.3 to pass Irons.

Midway through his morning heat, O'Brien rode through a long double-barrel at Backdoor Pipeline and made it out both times for a score of 46.2.

"I feel fortunate to make it out of that barrel," he said. "There weren't that many good ones today, so I'm glad I got that one."

O'Brien's best three waves over the three days of the contest scored a total of 128.2. Irons was second with 127.2.

O'Brien received $50,000 for the win — a larger first-place check than any other surfing contest in all of 2007.

Irons received $25,000 for second, and Eleogram got $15,000 for third.

In another aspect unique to the Backdoor Shootout, surfers were split into four-man teams based on their sponsors. O'Brien represented Red Bull.

Quiksilver — Mark Healey, Tyler Newton, Danny Fuller and Reef McIntosh — took the top team honors.

"You had some of the best tube riders in the world, and we scored big, heavy Pipeline," Healey said. "I think every single guy in this contest had at least one crazy, amazing barrel. That makes it worth it."

TOP FINISHERS

1, Jamie O'Brien (Red Bull), 128.2 points. 2, Bruce Irons (Volcom), 127.2. 3, Ola Eleogram (No Fear), 113.1. 4, Marcus Hickman (Volcom), 107.9. 5 (tie), Mark Healey (Quiksilver) and Myles Padaca (Da Hui), 106.9. 7, Tyler Newton (Quiksilver), 105.9. 8, Makua Rothman (Oakley), 102.3. 9, Nathan Fletcher (Oakley), 102.1. 10, Reef McIntosh (Quiksilver), 101.0.

Reach Dayton Morinaga at dmorinaga@honoluluadvertiser.com.