Jose Zepeda climbed off the canvas four times before overcoming Ivan Baranchyk in an action-packed light-welterweight fight which saw eight knockdowns in five rounds.
Zepeda was felled twice in the opening round by cuffing blows while he and his Belarusian opponent traded knockdowns in the second at the MGM Grand in Las Vegas.
The frenzied nature of the contest continued as Zepeda dropped Baranchyk in each of the third and fourth rounds and despite being put down in the fifth, the American ended proceedings in the same round with a savage straight left.
Zepeda, who suffered a dislocated shoulder in a 2015 loss to Manchester's Terry Flanagan for the WBO lightweight title, therefore claimed the lightly regarded WBC silver title at 140lbs.
He said: "I feel great because I won the fight. It was a hard fight, and I'm thinking, 'Man, boxing is hard. It's no easy game'. Boxing, it's tough, and you have to give it 100 per cent because it's a hard sport.
"Both of us are climbing up, and somebody had to stay. I was able to win the fight, and I told him, 'Thanks for the fight. It was a great fight'.
"I know I'm tough. I didn't know how tough I was. I showed myself, too. I've never been in a fight like this. It was a great learning experience."
While Zepeda improved his professional record to 33-2, Baranchyk fell to 20-2 and has now lost two of his last three fights, having been outpointed by Scotland's Josh Taylor in their world title showdown in May last year.