Video by Ryan Burton

From Galen Center on the campus of USC in Los Angeles, Jermall Charlo (25-0, 19 KOs) retained his IBF Junior Middleweight World title with an emphatic fifth-round knockout over previously unbeaten, top-ranked Julian "J-Rock" Williams (22-1-1, 14 KOs).

Charlo dropped Williams three times, once in the second and twice in the fifth. Williams, who had not lost a round in 10 consecutive fights, went down for the first time in his career from a strong counter left-hand midway through the second round.

Williams, who established his counter right early, performed well for the next two rounds in the first title fight between undefeated 154-pound champions since Floyd Mayweather dismantled Canelo Alvarez in 2013.

But Charlo decked him again with a brutal right uppercut midway through the fifth round that sent Williams collapsing face-forward onto the canvas.  Williams got up, but he was clearly in trouble. Charlo floored him seconds layer with a left hook, forcing referee Wayne Hedgepath to instantly halt the contest at 2:06.

Charlo was ahead with scores of 38-37 on the three scorecards entering the fifth round in a highly skilled matchup between two fighters in their prime.