David Griffin bobs and weaves as his bare feet dance across the padded floor of the chain-link cage. His eyes narrow as they lock on their target and he unleashes a flurry of punches. Jab! Jab! Jab!

Griffin spins on one heel and wheels a high kick toward his trainer's thigh. Whaaap! He moves to strike again as a buzzer sounds, signalling the end of combat.

"That was great," trainer Matt Robinson says as Griffin sags against the fence, breathing hard. Sweat streams down his face and across his chiseled, tattooed forearms. He has 30 seconds to catch his breath before the next round begins.

Welcome to David Griffin's day off.

The 29-year-old Citadel graduate has spent the past five years battling blazes for the Charleston Fire Department, where he holds the rank of engineer. But now he's training for a much different kind of fight.

On June 11, Griffin will take on veteran fighter Houston "The Assassin" Alexander in a top-of-the-card, mixed martial arts bout at the North Charleston Coliseum. The fight, his biggest to date, is being dubbed "Clash at the Coliseum" and a "real life 'Rocky' story." It has landed Griffin's menacing stare on billboards and posters throughout the region.

It's a role the former baseball player never envisioned for himself while growing up around Charleston. But it's a destiny he's embraced since a tragedy caused him to take stock of life and meet new challenges head-on.

"I really enjoy it. Fighting is my form of therapy," Griffin says with a grin. "And it's not that much different from baseball. Instead of hitting a ball, I punch a guy in the face."

So when he's not riding Engine 102 and putting out fires on the peninsula, Griffin is in the gym and training -- hard. A typical day off can involve three 60- to 90-minute workout sessions, honing his skills, strength and endurance for a sport that combines elements of boxing, jujitsu, wrestling and Muay Thai kickboxing.

The workouts are so draining he can lose several pounds of water weight in a day. For dinner, he can down four cheeseburgers in a row just to keep his weight around 200 pounds.

As a kid, Griffin put his energy into baseball and became a standout shortstop at Stratford High School. He went on to play for The Citadel Bulldogs and later landed in the minor leagues for a spell. When his playing days came to an end, he joined the Fire Department and took up bodybuilding. "I never really had any desire to fight," he says.

He grew interested in mixed martial arts after watching some of the adrenalin-soaked matches on television. It seemed like a physical chess match in which fighters had to use strategy and skill, as well as brawn, to outlast opponents. He thought about giving it a try.

Then came the night of June 18, 2007. Griffin was on the first truck to arrive at the Sofa Super Store in West Ashley as a small trash fire grew into an inferno. He watched nine of his fellow firefighters enter the store and never return. It's a memory he still doesn't feel comfortable talking about, but one that has shaped his life in many ways since. "Everything I do is kind of based on that."

Griffin realized life was too short to take for granted, to let dreams and opportunities pass him by. He enrolled in graduate school and began working toward his master's degree, with an eye toward becoming a college-level fire instructor. He also decided to take a stab at becoming an ultimate fighter and test his mettle in the cage.

Some of his fellow firefighters initially had a tough time believing Griffin was entering the world of ultimate fighting. It's not that they didn't think he was up to the challenge. He is a walking mass of coiled muscle. It's just that, well, he seemed like too nice a guy to revel in a sport Sen. John McCain once dubbed "human cockfighting."

Griffin says the sport has come a long way from its no-holds-barred past. The fighters are better trained, more professional, keen on strategy. Griffin certainly doesn't come across as a street brawler of old. He speaks in soft tones, punctuates his answers with "sir" and "ma'am" and has classical music greet callers on his cell phone.

Trainer Robinson, who runs Charleston Krav Maga on Wappoo Road, says Griffin exemplifies the modern approach to the sport. Robinson, a third-degree black belt with 17 years of experience in martial arts, says Griffin takes every lesson to heart and relentlessly practices until he perfects each new technique.

"He's probably the fastest growing fighter I've ever seen," Robinson says. "He's going to go places."

Griffin says he draws inspiration from his fellow firefighters and his wife, Melissa, who has been in his corner from the start. Since last August, Griffin has compiled a record of three wins and one loss. He's also finished his master's degree and is about to get to work on a doctorate.

When he enters the cage, Griffin will be wearing a shirt memorializing the nine firefighters who died. The Fire Department's honor guard will accompany him as he enters the coliseum to the sound of bagpipes playing "Amazing Grace." It's his way of paying tribute, of making sure no one forgets.

"It means a lot to me," he says. "The whole reason I'm in there fighting is to keep their memories alive."