Brian Viloria had a lot of incentive to defend his 108-pound title against Carlos Tamara.

The 29-year-old veteran was fighting in the Philippines, his ancestral homeland, which has embraced him, and a proposed showdown with undefeated world champ Ivan Calderon awaited him if he could turn back the challenge of the Colombian Olympian.

But Tamara (21-4, 15 knockouts) would not be denied on Saturday (Philippines time).

Fighting like a man possessed, the 26-year-old challenger survived Viloria’s early success, fought through swollen eyes, and put forth a savage late-rounds rally that the titleholder could not survive.

Tamara overwhelmed Viloria (26-3, 15 KOs) along the ropes in the final round of the bout, forcing referee Bruce McTavish to step in at 1:45 of the 12th and save the titleholder.

Viloria was never off his feet but he was absolutely spent after trying to withstand Tamara’s relentless attack.

Over the first half of the entertaining contest it was Viloria who dished out the punishment by beating Tamara to the punch from the outside and ruthlessly pounding the Colombian’s body when the two engaged on the inside.

However, the taller, rangier Tamara never strayed from his jab, which prevented Viloria from mounting a consistent attack and eventually allowed him to set up body-head combinations that weakened the titleholder.

Once Tamara was able force Viloria to the ropes in rounds six, seven and eight, he outworked the natural counter puncher. By rounds nine and 10, Tamara was doing more than out-hustling Viloria, he was punishing the Filipino-American who was on the 2000 U.S. Olympic team. Tamara administered such a sustained beating in the 11th, the round could have been scored 10-8 in his favor even though Viloria was never off his feet.

Viloria gamely fought back in spurts throughout Tamara’s spirited assault down the stretch of the fight but he was simply out of gas in the final round and done in by an accumulation of punches.

“I came here to win and my conditioning, desire and motivation to become a world champion is what got me through,” Tamara, a late substitute, said after the fight.

The loss has to be hard pill to swallow for Viloria.

He suffered his first knockout and for the second time in his up-and-down nine-year career a loss to an underdog ruined his management's plans for a high-profile, big-money matchup.

During his first title reign there had been talks of matching Viloria with Japanese star Koki Kameda, who held a 108-pound title at the time.

However, Viloria lost to Omar Nino Romero and then failed to win his next two bouts.

Viloria, who contemplated retirement before giving the sport one more chance under the guidance of boxer-turned-trainer Roberto Garcia, pulled himself out of obscurity with an eight-bout win streak that includes a title-winning TKO over Ulises Solis last April.

After defending his title against Jesus Iribe in his native Hawaii last August, Viloria was on the cusp of something big before he ran into Tamara.

Viloria’s shot at Calderon may now go to the battle-tested and iron-chinned Colombian. At least, that’s what Tamara hopes.

“I know (Viloria) talked about Calderon and Calderon wanted to fight Viloria, but what about me? I just beat Brian Viloria,” Tamara said.