Imagine a boxer having to fight twice in one night for a title belt. Or a football team having to play two playoff games on the same day.

That's what four competitors will get a chance to do at tonight's Rumble on the Rock 9 mixed martial arts event at the Blaisdell Arena.

The highlight of the card will be the semifinals and final of a 175-pound championship tournament.

In one semifinal, Jake Shields of San Francisco will face Japan's Yushin Okami. In the other semi, Carlos Condit of New Mexico will take on Frank Trigg of Los Angeles.

The semifinal winners will then meet for the championship in the final bout of the card. The winner of the final will be crowned the ROTR organization's inaugural world welterweight champion.

"There's no politics involved," Shields said. "It's about as fair a way you can have to determine a champion."

The quarterfinals of the tournament were staged in January, so the semifinalists basically had three months to prepare for tonight.

"You have to train differently because you have to train for two fights," Condit said. "But I think if you want to be called a world champion, you have to earn it, and the winner of this tournament will definitely earn it."

As Trigg put it: "There's four guys left and you have to train yourself for three of them. It'll take a special fighter to win this."

Trigg is 13-4 and ranked No. 5 in the world. He is considered the favorite to win the tournament — a role he welcomes. "I'm the favorite, and I feel like I should be," he said.

Trigg is also one of the most recognized figures in mixed martial arts. When not competing, he does color commentary on national and international broadcasts of MMA events. He also has his own line of clothing called "Triggonomics."

"I am a professional athlete in the true sense in that I have to take every opportunity that presents itself," he said. "As long as it will not interfere with my training schedule and not hinder my ability to be a professional athlete, then I'll take a look at it and see if it makes business sense."

Trigg's semifinal opponent, Condit, is looking for an upset, just like he did in the quarterfinals. Condit beat Renato "Charuto" Verissimo de Oliveira in the quarterfinals with a stunning first-round knockout.

"I'm definitely the underdog — everybody in the MMA world knows Trigg," he said. "But that makes me dangerous because I have nothing to lose."

At 21, Condit is the youngest competitor in the tournament. He has a professional record of 14-2, but is not even mentioned in the world rankings. A tournament championship could change that.

"I've kind of made a blip on the radar," he said. "Now I just have to solidify my place there."

Shields is considered the favorite in the other semifinal. He is 12-4-1 and ranked No. 7 in the world.

"This is the toughest tournament ever done at this weight," he said. "If you win this, I think you have to be considered one of the top five fighters in the world."

Okami is 14-2, and won his quarterfinal bout when opponent Anderson Silva of Brazil was disqualified because of an illegal kick. Silva was considered a heavy favorite over Okami.

"It goes to show that anything can happen in this sport," Shields said. "You just have to be ready for anything."

NOTES

Brandon Wolff and Josh MacDonald will meet in an "alternate" bout for the tournament. If one of the semifinalists gets injured, the winner of the Wolff/MacDonald bout will be put in as a replacement.

Eric "Butterbean" Esch will take on Aaron Aguilera in a "Super Fight" co-main event tonight. Esch is listed at 5-11 and 350 pounds; Aguilera is 6-6 and 270 pounds.

Reach Dayton Morinaga at dmorinaga@honoluluadvertiser.com.