Under the circumstances, Brian Viloria is doing well.

The Waipahu boxer is listed in good condition at a hospital in the Philippines following a 12th-round TKO loss to Colombia's Carlos Tamara on Friday night.

Viloria collapsed in the locker room after the bout, and was rushed to a nearby hospital. He underwent a CT scan and several other medical tests Friday night and yesterday morning.

He will remain in the hospital for at least two more nights for observation, according to his manager, Gary Gittelsohn.

"Brian's condition is good — all his tests have returned normal and it is likely that his scary collapse in the dressing room following a brutal fight was the result of a concussion and/or dehydration," Gittelsohn said.

Viloria will also have to remain in the Philippines until doctors clear him for travel. Gittelsohn estimated that Viloria will be in the Philippines for "approximately 10 to 14 days."

Viloria lost his International Boxing Federation light flyweight world championship to Tamara. The world title bout was held at the Cuneta Astrodome in Manila, and received extensive media coverage in the Philippines.

Several media outlets in the Philippines followed Viloria to the hospital to provide live updates.

By most accounts, Viloria dominated the early rounds of the bout before Tamara rallied in the late rounds.

In the 12th — and final — round, an exhausted Viloria lost his balance and fell twice while attempting wild punches. According to GMA News in the Philippines, Tamara landed 14 unanswered punches, prompting referee Bruce McTavish to stop the bout at 1:45 of the 12th round.

"Viloria was very strong in the early rounds," Tamara said through an interpreter at the post-fight press conference. "But he was very, very tired in the late rounds."

Viloria was ahead on points on two of the three judges' cards after 11 rounds. However, Tamara's domination of the final round would have made for a close decision either way, had Viloria lasted the round.

Viloria dropped to 26-3 with the first knockout loss of his nine-year professional career.

He won the IBF light flyweight world championship in April 2009 with an 11th-round knockout of Ulises Solis in a bout also staged in Manila.

The bout against Tamara was Viloria's second title defense. Viloria, 29, is also a former WBC light flyweight world champion.

Tamara improved to 21-4 with the 15th knockout of his career. He was the No. 7-ranked contender by the IBF.