While the history of classic rematches in the Ultimate Fighting Championship is relatively short, the number of dud second encounters in boxing is plentiful. Whether it was the second meeting of Muhammad Ali and Joe Frazier or the return bouts to modern wars such as Marco Antonio Barrera-Erik Morales and Arturo Gatti-Micky Ward, rematches to great fights have generally been anti-climatic.

So the mixed martial arts world will be watching the return bout between BJ Penn and Jens Pulver at The Ultimate Fighter 5 finale in Las Vegas this Saturday in hope that the UFC will not follow boxing’s disappointing tradition.

The fighters’ initial meeting on January 11 2002 was a classic battle laced with skill, power and above all, pride.

Penn entered the Octagon that night as arguably the hottest fighter in the sport, and had deservedly earned his moniker ‘The Prodigy’. Having risen to prominence by becoming the first American-born winner of the black belt category World Brazilian Jiu-Jitsu Championship in 2000, the Hawaiian made the most of his opportunity in the UFC by stopping Joey Gilbert in the fist round. Penn then displayed surprisingly strong striking skills when needing less than a round to destroy highly respected fighters such as Din Thomas and Caol Uno.

His UFC 35 lightweight title clash with Pulver, who had been submitted by Thomas, was expected to be the official inauguration of Penn’s invincibility. But the Maple Valley, Washington native was no stranger to intimidating situations. Pulver grew up in a self-described “daily hell” thanks to his alcoholic father’s violent tendencies; pop was a belligerent figure who even threatened his young son with a firearm.

Steeled by the tough upbringing, Pulver showed no respect in the Octagon for Penn’s daunting reputation, even when the 3/1 betting favorite locked in a hold that pressurized Pulver’s arm to the point of hyperextension. Still, ‘Little Evil’ managed to best the supposedly superior grappler in the following rounds and stood toe-to-toe with Penn in a thrilling final five minutes on route to a majority decision victory.

The immediate rematch never materialized as both fighters ran into contractual issues with the UFC, and neither has managed to sustain their once-apparent promise. Pulver, 21-6-1, had mixed success competing primarily in Japan and his return to the UFC last September turned into disaster after he was stopped in 48 seconds by the unheralded Joe Lauzon.

Conversely, Penn scored a shocking upset over legendary welterweight Matt Hughes in 2004, using a rear-naked choke to take the champion’s title, but he was soon stripped of the belt after signing with a rival organization. Like Pulver, the Hawaiian’s recent return to the UFC has also been fruitless with tough losses at 170 pounds to Georges St. Pierre and Hughes in 2006.

Still, Saturday’s clash gives both fighters the chance to redefine their careers, and, even though rematches often lack the intensity of the original, the interactions between Penn and Pulver as coaches on TUF 5 indicate that their mutual animosity hasn’t waned over the years.

“They legitimately hate each other,” said Lauzon, who was a participant in the reality series.

“I've had to listen to ‘B.J. Penn this’ and ‘B.J. Penn that’. He’s like my archrival,” said Pulver, explaining the origins of his dislike for ‘The Prodigy’.

And Penn, 10-3-1, is willing to dispute anything Pulver says, even if it’s about who is the least favored.

“I’m not gonna let him sit there and say that he’s the underdog and that I’m gonna underestimate him,” Penn told writer Thomas Gerbasi. “I’m the underdog. I lost the first fight, and Pulver’s trying to put himself in the underdog position to pump himself up, but it’s different because I’m the one who’s hungry.

“How can somebody be the underdog and they beat you? I’m not gonna let him get away with that frame of thinking. I’m the underdog and I’m gonna smash him.”

But the differences between the two don’t stop at personalities.

“They’re polar opposites,” added Lauzon. “BJ is from a tight family. They had a lot of money in Hawaii. He had the ideal upbringing. Jens is the opposite. His family had to move around all the time. They lived at a dog track at one point. He was a poor kid.”

Said Penn, “[Pulver] brings that whole crowd from the Midwest, and those people relate to him and support him, and I represent the exact opposite on the other side in the Pacific and the people bordering the west coast, Hawaii and all throughout Polynesia. Plus, he’s the striker, I’m the grappler. He was the champion, I was the guy who was supposed to beat him.”

With a 155 pound title shot probably awaiting the victor, both fighters are approaching the contest with a ‘now or never’ attitude.

“This time around, mentally I'm right where I want to be,” said the 32-year-old Pulver, who has been based at the renowned Miletich Fighting Systems camp. “I'm right with myself. I'm just really motivated and that can't be broken.”

Likewise, Penn, 28, has been working on his psyche, isolating himself in his hometown of Hilo in an effort to eliminate all external distractions.

“I haven’t really been anywhere or flown anywhere. I’ve been in Hilo since the [TUF 5] show started, and I just trained every single day until right now.”

But surely Penn will be relieved when the fight is over and he can finally end his acrimony with Pulver?

“We'll cross that road when it gets there,” he said. “Let's just see what happens that night.”

With that sort of resentment, Saturday’s rematch may force the UFC to adopt one of boxing’s more celebrated traditions…trilogy, anyone?