Since losing by unanimous decision to Celestino Caballero in May of 2005, Daniel Ponce De Leon reeled off seven straight wins, captured and defended four times the WBO 122-pound title. Of those seven wins, five have come by knockout for the hard-hitting Mexican.  In a rematch against Sod Looknongyangtoy in July of 2006, the man De Leon defeated for the vacant title nine months earlier, Ponce scored a knockout so devastating that it topped almost every list for knockout of the year.  Saturday night on HBO Boxing After Dark, Ponce De Leon, 31-1 (28 KOs), is defending his title against one of the most talented fighters he's ever faced, undefeated slugger Rey "Boom Boom" Bautista, 23-0 (17 KOs).   Both fighters have very good knockout ratios for the 122-pound division and are destined to set off fireworks in Saturday's main event.  With the two recent super fight slugfests between fellow super bantamweights Rafael Marquez and Israel Vazquez, the winner De Leon-Bautista hopes to be next in line, along with Caballero who now holds the WBA title.