Terence Crawford knocked down Egidijus Kavaliauskas three times before stopping him in the ninth round on Saturday night to remain unbeaten and defend his welterweight title.
Kavaliauskas had never been knocked down as a pro and Crawford said this week he couldn't recall even seeing him hurt.
But Crawford dropped the challenger once in the seventh round and twice more in the ninth before referee Ricky Gonzalez stopped it at 44 seconds of the round.
Crawford absorbed perhaps more shots than usual but seemed to enjoy getting to show he has power, too, letting out a big smile as Kavaliauskas returned to his corner looking frustrated after one round late in the fight.
The Lithuanian, who was the mandatory challenger for Crawford's WBO belt, had some good moments in the first few rounds before Crawford took control midway through the fight and then poured it on late.
Crawford took a hard shot early in the seventh but then began answering and finally caught Kavaliauskas with a looping right near the ear that sent him to the canvas.
The 32-year-old finished it two rounds later, using a three-punch combination to set up a right uppercut that sent Kavaliauskas to the canvas.
He got up but Crawford then threw a right hook that returned Kavaliauskas to the canvas and the fight was immediately waved off.
On the same bill, Teofimo Lopez ripped the IBF lightweight belt from Richard Commey with a ruthless knockout win.
The Brooklyn fighter dropped Commey with a big right hand and forced a second round stoppage victory over the Ghanaian.
Vasiliy Lomachenko then joined Lopez in the ring to spark speculation of a possible unification clash in 2020.