Roman Gonzalez stopped Omar Soto 36 seconds into the second round in the third defense of his WBA junior flyweight title on the Toshiaki Nishioka-Rafael Marquez card Saturday in Las Vegas.
Gonzalez (30-0, 25 knockouts) landed a straight right and then a left uppercut to put Soto (22-8-2, 15 KOs) on his back, where remained for the count.
Gonzalez, a Nicaraguan who fights for a Japanese promoter, was making his debut in the United States.
Soto, from Mexico City, has now failed in three attempts to win a major world title.
In an earlier bout, welterweight prospect Yoshihiro Kamegai (19-0, 17 KOs) of Japan stopped Hector Munoz (19-7-1, 12 KOs) at 1:39 of the sixth round of a scheduled 10-round fight.
Kamegai, also making his U.S. debut, wore down a game Munoz with non-stop pressure, consistently landing hard punches to the head and body.