The Associated Press

In the days leading up to his heavily anticipated title bout at UFC 94 in Las Vegas, BJ Penn has made an improbable proclamation.

He says that welterweight champion Georges St. Pierre is a quitter who won't have anything left if Penn can just survive the initial onslaught of arguably the best pound-for-pound mixed martial artist in the world.

''That's how I'm going to beat him, because I'm going to get through all of his skills,'' said Penn, who is from Hilo. ''You know he's tough and he's all of these things, but once I get through, he's going to be empty on the inside, and that's how I'm going to finish him.''

St. Pierre (17-2-0) might be the favorite in Saturday's rematch of the two top UFC stars' March 2006 bout - he won that one by split decision - but Penn (13-4-1) is far from a one-in-a-million underdog after winning the lightweight title early last year and defending it in May.

''I love to be the underdog,'' Penn said. ''I haven't been the underdog for a long time. Fighters who don't believe I can win this fight, it's simply because they don't believe in themselves, that they could go out and beat a great champion at a higher weight.''

With a new dedication to training, Penn has been good enough in his recent fights to make the matchup at the MGM Grand Garden an entertaining cap to a remarkable three-month run for UFC under the Vegas lights, following Brock Lesnar's heavyweight title victory in November and Rashad Evans' win over Forrest Griffin last month.

St. Pierre and Penn have been featured on a three-part reality television show dedicated to their preparations for this showdown, and UFC president Dana White predicts the most pay-per-view buys in the sport's history.

''You're lucky if you get to see three or four of these types of fights in your lifetime,'' White said. ''Two of the best fighters in the world in their weight classes, both champions facing each other both in their prime. This fight is a Hagler-Hearns. This fight is Hagler-Leonard.''

With a win over St. Pierre, Penn would be the first fighter to hold UFC titles simultaneously in two weight classes.

St. Pierre, however, has lost only to former welterweight champ Matt Hughes. The Montreal native beat Penn by a memorably contentious split decision in their first fight nearly three years ago.

''It's like when you play cards,'' St. Pierre said. ''You don't show your hand. I've been studying a lot of tape. He's a very well-rounded fighter, and that's why he's so good. On the other hand, I think I have the answer to that problem. I don't have a specific thing that I'm going to beat him with. I have a game plan, and I'm going to stick to it.''

The bout could hinge on Penn's ability to stop St. Pierre from taking him to the canvas. St. Pierre's wrestling prowess is well-known to Penn, who was taken down in the second and third rounds of their earlier bout.

''He's going to try to kick me hard,'' Penn said. ''He's going to try to punch me hard. He's going to try to slam me on my head. When he realizes he can't get that takedown, then he's going to realize he's in a fistfight, and then he's going to realize who he's going up against.''

Penn hasn't fought at 170 pounds since September 2006, when he lost for the third time in four fights at 170 or 185.

Penn, the first American-born man to win a world jujitsu title, thinks he wasn't nearly at the peak of his abilities when he lost to St. Pierre nearly three years ago. Penn claims he has only recently begun to tap his true potential, swearing off drinking and partying for a life of proper conditioning, diet and coaching.

''I definitely wasn't working as hard,'' Penn said. ''I didn't have the drive. I was just kind of inching by, and just getting through fights and getting through life.

''He's good at everything, and I don't have a specific technique that I'm going to beat him with. I'm just going to beat him with my mind and with my heart.''