It's being hyped as a David vs. Goliath bout.

But what happens when David is so good, he doesn't even need a slingshot?

That's the kind of intrigue surrounding tonight's mixed martial arts bout between Jason "Mayhem" Miller and Stefan Gamlin. It is the main event of the Icon Sport card at the Blaisdell Center Arena.

"If I'm in a fight, there's always something to lose — the fight," Miller said. "So I go in to win no matter who it is or how big the guy is. I wouldn't be in this fight if I didn't think I could win."

Tonight's main event is a rare open weight bout.

Miller is 6 feet 1 and the No. 1 contender in Icon Sport's 185-pound class. Gamlin is 6-7 and weighed 370 pounds when the bout was first announced last month. He said he is now down to "about 350."

"People will look at it and say I'm bigger and all that, but this is a really good matchup," Gamlin said. "This guy I'm fighting is a top professional with a good record. I'm kind of new to this stuff."

Miller is 25 and has a professional MMA record of 14-4, including 5-0 in Hawai'i.

Gamlin is 35 and has an MMA record of 0-2. He said most of his previous fighting experience came in "Toughman" competitions, which is more like boxing.

"Obviously, I want to make this a quick fight," Gamlin said. "I have to knock him out early. If it goes long, or if he gets me on the ground, it'll be to his advantage."

The bout is scheduled for three 5-minute rounds.

Miller prepared for the bout by lifting weights and wrestling with "big dudes." He said he will weigh around 200 pounds for tonight's bout. Miller is a jiu-jitsu expert, and nine of his victories have come via submission.

"I really don't know what's going to happen," Miller said. "I imagine (Gamlin) is going to be aggressive. I just have to be ready for that and try to win the fight any way I can."

What Miller lacks in size, he should make up for in training. He is a full-time professional fighter, and has been training daily in Honolulu for the past few months.

Gamlin has a full-time job as a sales representative for an equipment rental company in Arizona.

"I wake up at 4:30 in the morning, and I'm working all day," he said. "I fit in my training at night, and to be honest with you, I'm exhausted just going to the gym sometimes. But this is fun. It's a hobby for me, and if I'm successful (tonight) I may look into more opportunities."

Tonight will also be Miller's first bout since Oct. 28, when he defeated Falaniko Vitale to become the No. 1 contender.

Miller was suspended for four months by the Icon Sport organization after his arrest on a charge of first-degree burglary. The case has yet to go to trial.

"I want to give the fans something to cheer about again," Miller said. "I've been dying not being able to fight for the fans."

Regardless of tonight's outcome, Miller will remain the No. 1 contender. He is expected to face champion Robbie Lawler later this year.

SCHEDULED BOUTS

Open weight: Jason "Mayhem" Miller vs. Stefan Gamlin. 135: Bill "Spider" Dexter vs. Tyson Nam. 175: Anthony Torres vs. Jerry Hackney. Heavyweight: Ray Seraille vs. Gary Myers. 170: Lawrence Shorter vs. Sydney Silva. 155: Kaleo Kwon vs. Marshall Harvest. Heavyweight: Pat Collins vs. Jarret Lindsey. 165: Kimo Lee vs. Derek Stadler. 190: Ron Verdadero vs. Jack Richardson. 135: Jared Santos vs. Ikaika Silva. 130: Bronson Mohika vs. Devin Damo.

Reach Dayton Morinaga at dmorinaga@honoluluadvertiser.com.