Randy Couture and Mark Coleman have been headed for this fight since the UFC's event numbers were in the teens.

These two pioneers of mixed martial arts are now in their mid-40s, and they've been circling each other since their sport's infancy. During the years when Coleman fought mostly in Japan, when Couture became an actor in his spare time away from the octagon, they never stopped anticipating a fight that nearly happened in 1998.

"I think it would have been just as interesting 10 or 12 years ago," Couture said. "We were both a lot less refined as athletes and combatants back then, but it would have been a hard-nosed affair. Mark and I are both straight-up competitors, and it would have made for a great fight."

The UFC still expects a great, long-overdue fight when the 46-year-old Couture takes on the 45-year-old Coleman at UFC 109 at the Mandalay Bay Events Center in Las Vegas on Saturday night.

Couture and Coleman are living, thriving proof the benefits of ambitious training, even if the rough-and-ready Coleman started getting serious about longevity a whole lot later than Couture. They also stand as evidence of the relative safety of MMA, which hasn't broken either of these two eager fighters.

While the fighters' combined age is easily the biggest in the history of UFC's main events, this is no sideshow. Although Couture (17-10) is the favorite to claim the victory and a likely light heavyweight title shot against Lyoto Machida or Mauricio "Shogun" Rua, Coleman (16-9) thinks he can continue his improbable late-career resurgence.

"This is by far the biggest fight of my life," Coleman said. "I've been in some big fights, but none of them compare to this. There's a lot on the line for me. ... That's about the No. 1 question I've been asked by everybody for about the last 10 years: When are you going to fight Randy?"

The bout is Couture's third time in the octagon in less than six months, a remarkable stretch for a fighter who hasn't been this busy in more than eight years. Couture has plenty of interests outside the ring, with a burgeoning acting career and businesses that demand his time.

Yet when a series of injuries to UFC's top stars left president Dana White a bit short on names, Couture was thrilled to step in as a headliner.

"Randy Couture is a testament to God knows what," White said. "I don't know what he eats and does, but everybody should be eating and doing it. These guys have both been fighting at the top of the game for who knows how long, and the big thing is these guys really wanted to fight each other. They can both still compete and work hard. There's no doubt about either of them."

The UFC's first major card in a month also features 185-pound contender Nate Marquardt against Chael Sonnen, Paulo Thiago's 170-pound return against Mike Swick, and former welterweight champion Matt Serra's return from an eight-month absence against Frank Trigg.

Couture and Coleman actually fought once before _ at the 1989 Olympic wrestling festival in Stillwater, Okla., where Coleman won by one point. They were slated to meet at UFC 17, back when purses were a fraction of their current size, and Couture pulled out to prepare for a national wrestling tournament.

Couture actually contributed to Coleman's revival when he allowed Coleman to train for his most recent fight at his Xtreme Couture gym in Las Vegas. Coleman surprised 32-year-old Stephan Bonnar with a unanimous decision at UFC 100, and was in line to fight Tito Ortiz late last year before getting injured in training.

Coleman was crushed by missing what he thought might be his last chance at a big payday. After a career in which he acknowledges lapses in his training and discipline, Coleman finally feels comfortable leaving his children at home in his native Ohio to chase UFC glory.

"I felt like I lost out on a huge opportunity, and I didn't foresee being able to top that matchup," Coleman said of his injury pullout against Ortiz. "I anticipated maybe fighting a younger guy and being a gatekeeper."

Coleman helped to define the brutish MMA style known as ground-and-pound, while Couture has remained competitive with a well-rounded approach. Neither fighter is likely to overwhelm his opponent with dazzling striking abilities, so the fight could be decided by endurance _ and both of these 40-something fighters have plenty.

After they finally meet, neither fighter expects to be finished. Both Couture and Coleman intend to keep pursuing their MMA career to the doorstep of 50.

"This is what I do," Coleman said. "This is what I love to do, and I'm still willing to put in the time. ... If losing a fight is the worst thing that happens to you in your life, you're doing pretty well."

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