It's not often you think of small boxers flyweight and featherweights as knockout kings. Lacking the mass that the big boys do, these hitters owe their successes to supernatural endurance and sound technical ability. But not Cuban boxer Yuriorkis Gamboa. The former Olympic gold medalist has fought and won professionally 13 times now, and only two of those times did the fight reach decision. Each other victory has come by way of Gamboa's powerful combination of lightning fast flurries and stop-you-in-your-tracks knockout blows. He'll look to build upon his five first-round knockouts when he faces veteran Colombian boxer Walter Estrada during tonight's nationally televised ESPN 2Friday Night Fights, billed as The Gunslingers. Talk is this may be Gamboa's final challenge before he earns himself a title fight.