Unbeaten at 155 pounds for nearly 8 years, BJ Penn has ruled the lightweight division with an iron fist, finishing top contenders Joe Stevenson, Sean Stark and Kenny Florian along the way. The Prodigy will face a challenger as willing as he is to leave it all on the line in Diego Sanchez, who has reinvented himself as a relentless cardio machine that won t stop moving forward until he wears the UFC Belt around his waist.