Joseph Diaz Jr. of South El Monte stopped overmatched Noel Mendoza of Phoenix at 1:54 of the third round Saturday night at StubHub Center.
Diaz decked Mendoza (6-3) twice in the third round, referee Raul Caiz Jr. waving off the bout after the second knockdown.
Diaz, a 2012 U.S. Olympian, is now 7-0 with five knockouts. His bout was televised on Showtime Extreme.
Joseph Diaz Jr. of South El Monte is 5-0 with three knockouts after stopping Rigoberto Casillas of San Diego after the third round of their scheduled four-round featherweight bout on Saturday at Home Depot Center in Carson.
Diaz, a 2012 U.S. Olympian, battered Casillas (8-12-1) with hard shots to the head and body. Casillas did not answer the bell for the fourth round.
Joseph Diaz Jr., a 2012 U.S. Olympian from South El Monte, is now 4-0 with two knockouts after stopping Eric Gotay in the third round of their super bantamweight bout Friday at the Cosmopolitan in Las Vegas.
Diaz, just 20, trains out of the Teamsters Youth Boxing Club in South El Monte. His bout with Gotay was scheduled for six rounds. Gotay, of the Dominican Republic, is 3-2.