Oscar Collazo predictably obliterated Reyneris Gutierrez in their 105-pound title fight Saturday night in Phoenix.

The powerful Puerto Rican southpaw dropped Gutierrez in the third round and continued to hurt the huge underdog until referee Chris Flores stepped between them to halt the action at 2:37 of the third round. Collazo’s victory came in the co-feature on the Jamie Munguia-John Ryder undercard.

The 27-year-old Collazo (9-0, 7 KOs), a Newark, New Jersey native, made his second defense of the WBO 105-pound championship.

Nicaragua’s Gutierrez (10-2, 2 KOs), who is ranked 10th by the WBO, was a huge underdog. Most sportsbooks listed Collazo as at least a 30-1 favorite entering this optional title defense.

Gutierrez has also lost two of his past three fights. Australia’s Alex Winwood, who entered the ring 2-0, unanimously outpointed Collazo last June 23 in Northbridge, Australia.

Collazo connected with a straight left with about 1:25 to go in the third round. Collazo later landed a left hand to the side of Gutierrez’s head that knocked him to the canvas.

Gutierrez got up in time to beat Flores’ count, but Collazo overwhelmed him with power punches and caused Flores to stop the bout.

Back-to-back right hooks by Collazo connected just after the midway mark of the second round. A few seconds later, Collazo nailed Gutierrez with a straight left that knocked Gutierrez off balance.

Collazo caught Gutierrez with a right hook that backed him up late in the first round.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing