After a whirlwind run on the Mainland to the top ranks of mixed martial arts, Hilo's BJ Penn will fight in Hawai'i for the first time tonight.

Penn, who is nicknamed "The Prodigy," will face Japanese champion Takanori Gomi in the main event of "Rumble on the Rock" at the Blaisdell Center Arena.

"Everything is on the line in this one," said Penn, 24.

There are various organizations in mixed martial arts, but by most accounts, Penn and Gomi are considered the two best lightweights (155 pounds) in the world.

Penn is 5-1-1, and his meteoric rise in the Ultimate Fighting Championship (UFC) organization has made him a popular draw on the Mainland. The UFC is considered the most watched organization in the sport.

"I pretty much had to fight all the top guys from day one," Penn said. "It was good because it helped my career. But it also hurt me because I lack experience to this day."

Still, his success has allowed him to open his own mixed martial arts gym in Hilo.

Penn was signed by UFC shortly after winning a jiu-jitsu world championship in 2000. Despite practicing jiu-jitsu for less than five years with the Nova Uniao team in Hilo, he became the first non-Brazilian to win a world title in Brazil.

"I was a punk when I was younger, and I got my (butt) kicked by guys who were older and tougher," he said. "That's actually why I got started (in jiu-jitsu). I wanted to beat up all those guys who made trouble to me."

Now, he's beating up the best fighters in the world.

Four of Penn's five victories have come by knockout, and his only loss was by decision to then-UFC champion Jens Pulver. Penn has fought before crowds of around 15,000 in Las Vegas and Atlantic City, but he said he will probably be more nervous tonight.

"I was having fun fighting in the UFC," he said. "I always wanted them to do a show in Hawai'i, but they never got around to it. When I found out I could fight Gomi and fight in Hawai'i, I said 'let's do it.' It's basically me and him (as) the top two, so this is huge."

Gomi is 13-1 and the champion of Japan's Shooto organization. That title will be on the line tonight, as well as the vacant Rumble on the Rock title.

An undisputed champion has been assured to emerge. The bout is scheduled for three five-minute rounds. If the judges declare a draw after the three rounds, the bout will continue until a winner is decided.

Other Hawai'i fighters scheduled to appear include Ray Cooper, Ronald Jhun, Stephen Palling and Kawika Pa'aluhi. All the bouts will take place in an octagon-shaped ring surrounded by a cage.