``Initially I was salivating because I was like, `Oh, I have the next big heavyweight star,' '' Allan said. ``It was close to the end of the lesson that someone informed me that I was actually training Glen `Big Baby' Davis from the Celtics .''

Despite the disappointment that he hadn't uncovered a future UFC star, Allan went to work with Davis. And there was no kid-glove treatment for the professional athlete. Though Allan said his top priority always was to avoid injury, Davis was put through rigorous daily workouts.

``With a name like Big Baby, when I found out that's what he was called, I was a little surprised because he was all business,'' Allan said. ``He comes in here and he knows what I want him to do. When I tell him what to do, he does it. There's no hesitation. He works hard, and he loves it, which helps.''

Davis had long been a fan of MMA. He decided to get involved in the sport over the summer after watching his girlfriend participate in amateur Muay Thai competitions.

``I love the UFC but I didn't really get into it like that,'' Davis said. ``But when I started watching her, and then I started to do it, then I was like, `Oh man, this is crazy. I love this.' After that it was just nonstop UFC - who's fighting, where is the fight, when am I training? It was just an unbelievable feeling.''

Though MMA is a violent sport, Davis understands that Basketball is his No. 1 priority and he isn't about to step into the ring. Instead, he has taken to the grueling cardiovascular training MMA fighters endure.

``I kind of felt like, `Oh man, Basketball is hard,' but when you're training for a fight, you have to go to a whole different level,'' Davis said. ``The training is so extreme. I thought I trained hard playing Basketball, but when you're doing mixed martial arts, you have to train even harder.''

With Davis' weight closely monitored, the Celtics are happy to see his enthusiasm for the offseason workouts.

``I like when guys go outside of their norm to train,'' C's coach Doc Rivers said. ``I think it's good for them. That's what he should do. I'm never impressed with a guy getting in shape for his job. . . . What I am impressed with is I think it shows a sign of maturity that they're understanding that this is what they need to do.''

Davis was listed at 289 pounds last season, but the number on the scale can be overrated. He is big, and the Celtics want him to be big. The team also wants him to be strong and in good shape, and he says his MMA training has helped him achieve that.

``I've kind of added on a lot of muscle. That was the point,'' Davis said. ``My game is I'm a big guy. I pound. That's what I do. So if I lose a lot of weight, I'm like the average player. I want to stay in my body frame and my weight, but (be) more conditioned and more toned.''

But for all of the improvements to Davis' core strength, he believes the biggest benefit has been his mental approach.

``It's like you can't quit,'' Davis said. ``In Basketball you can't quit. And also composure (is a benefit). You have to stay composed. When you're in a fight, you can't be wild or out of control. You have to control your breathing and you have to understand what's going on to understand what you have to do to win the fight.''

Davis' dedication was enough to turn Allan into a Celtics fan. And while the start of the NBA season will cut into Davis' time at Wai Kru, he plans to continue the training.

``I fell in love with mixed martial arts,'' Davis said. ``I just can't stop . . . I feel like it's helped me a lot. I'm going to continue doing it until I can't do it anymore.''

- danduggan@bostonherald.com