Kelly Slater is trying to stay focused on what he's about to accomplish.

The 39-year-old is about to further pad his resume as the most successful professional surfer ever. With a winning heat today in the Association of Surfing Professionals' Rip Curl Pro Search in San Francisco, Slater will clinch his 11th world title.

"I'm going to try and just be relaxed about it because it's a situation where you could feel tense and want to get it over with it," Slater said in quotes provided by the tour. "The reality of it is the other guys have to win both events with my last heat win so the pressure is on them.

Slater, the contest's defending champion, advanced past the first round Tuesday, earning 16.03 points out of 20 to win his heat. All he needs is a ninth-place finish or to advance through one more heat today to secure the title.

"I don't feel like I can relax, though, because the guys now have to focus and that's when they could do something magic. That's how it goes in competition and I don't doubt that that's a possibility," Slater said. "I just need to catch four good waves in this event to win the title."

Slater's accomplishments were somewhat overshadowed on Tuesday when Dusty Payne, 22, of Hawaii said he saw a large shark during his heat at Ocean Beach.

"I was just sitting there, and I was waiting for a wave. I've seen dolphins before and it wasn't a dolphin," Payne said during an interview on the beach with the Rip Curl Pro Search event's camera crew right afterward. "It was the biggest fin I've ever seen in my life coming straight at me."

A contest boat floating just offshore called in after the alleged sighting, saying they saw a dolphin, not a shark, said Dave Prodan, media director for the ASP.

"This obviously doesn't preclude the situation of having both a dolphin and shark in the water at the same time, and event organizers launched a jet ski to further assess the situation," Prodan said.

"Aside from Payne's initial report, no further sighting of the animal was confirmed and the competition resumed without pausing."

The sighting follows an attack by a 9-foot shark on a surfer Saturday at Marina State Beach in Monterey County, about 100 miles south of San Francisco. While the frigid waters off San Francisco are known to host to white sharks, attacks are rare.

Despite the alleged sighting by Payne, the contest continued.

It's the first professional surfing event in San Francisco in decades.

The sighting follows an attack by a 9-foot shark on a surfer Saturday at Marina State Beach in Monterey County, about 100 miles south of San Francisco.

Eric Tarantino suffered injuries to his neck and arm, but was released from the hospital Monday.

While the frigid waters off San Francisco are known to be host to white sharks, attacks are rare. The last attack, which was not fatal, occurred Nov. 2, 2005, according to the Shark Research Committee.

Slater also said that today marks the one-year anniversary of the passing of professional surfer Andy Irons and said that clinching his 11th title would be second to remembering his friend.

"The globe's a cool trophy and if I happen to make it out of the next round, I've love to win this contest," Slater said. "Tomorrow is the one-year anniversary of Andy's passing away, and it's going to be a sad and happy day in remembering him If I can win the world title on that day, it'd be secondary to the memory of Andy."

The Rip Curl Pro Search will continue until Nov. 12.

Rip Curl Pro Search

What: Tenth stop out of 11 on the ASP World Title Series

Where: Ocean Beach, San Francisco