Unbeaten Terence Crawford made a successful defence of his WBO welterweight title on Saturday, stopping Shawn Porter in the 10th round in Las Vegas.
The 34-year-old Crawford knocked Porter down twice in the 10th before Porter's father and trainer Ken Porter stepped in to call off the fight.
Crawford felled Porter intially with a left uppercut on the button that buckled his knees.
It was all over 1:21 of the round, when Crawford's overhand right to the side of the head sent Porter to the canvas for a second time, prompting his father to lean over the ropes and ask the referee to halt the contest.
Crawford improved to 38-0 with 29 wins by knockout, while Porter suffered the fourth loss of his career, falling to 31-4-1 with 17 KOs.
The fight was close through the first nine rounds with both fighters suffering cuts over their eyes due to accidental butts.
Crawford moved to 16-0 in world championship fights and extended his streak of winning inside the distance to nine straight bouts.
Crawford is considered one of the best pound-for-pound boxers in the world.
He was the undisputed champion at super lightweight, held a lightweight belt and is now 6-0 with six knockouts as a welterweight.
Crawford has the lesser of the four major welterweight titles.
Errol Spence, who was at ringside on Saturday, holds the IBF and WBC belts and Yordenis Ugas is in possession of the WBA title.
