It's no secret Brian Viloria and Ivan Calderon are on a collision course to determine the best 108-pound boxer in the world.

For it to happen, Viloria (26-2, 15 KOs) can't afford to slip up in the Philippines tomorrow (7 tonight, Hawaii time).

The IBF light flyweight champion defends his title against Colombian Carlos Tamara at the Cuneta Astrodome in Manilla.

(The fight is not available in Hawaii on pay-per-view).

Tamara, the mandated challenger as selected by the International Boxing Federation, is 20-4 with 14 KOs and, like Viloria, is a former Olympian.

“;He's a very capable fighter,”; Viloria said in a phone interview yesterday from Manila. “;I need to use a lot of head movement, work the body, put combinations together and just try to keep a very high pace.”;

Tamara, who competed in the 2004 Olympics in Greece, is on a three-fight winning streak since losing his only other world title fight, a unanimous decision loss to WBO flyweight champion Omar Andres Navarez in 2008.

“;He's a very serious challenger,”; said Viloria's manager, Gary Gittelsohn. “;Carlos has never been stopped, so Brian is prepared to go 12 rounds.”;

This is Viloria's first fight in the Philippines since his knockout of Ulises Solis last April to become a world champion for the second time.

A win over Tamara sets the stage for a unification fight with Calderon, the WBO champion at 108 pounds. There have been rumors of a two-fight deal between the two, with one to take place in Hawaii, but Gittelsohn said yesterday those talks are premature.

“;It hasn't even been discussed,”; he said. “;Right now the focus is on Carlos, and that's our only concern.”;