Oscar Collazo is definitively moving on up.

The 29-year-old pound-for-pound star last fought in June, when he made quick work of Neider Valdez in his flyweight debut. Collazo still owned the WBA, WBO and The Ring minimumweight titles at the time of the fight, but he has all but confirmed the weight change will be permanent.

Although he just defended the titles with a win over Jesus Haro in March, Collazo's WBO mandatory defense against interim champion Ryusei Matsumoto was about to head to purse bids. Instead of facing that situation, the Mexican is vacating the WBO 105-pound belt, the organization announced on Monday.

"Oscar Collazo has formally relinquished his WBO mini flyweight world title, bringing an outstanding championship reign to a close," the WBO stated in a tweet. "The WBO recognizes Collazo's remarkable legacy, professionalism, and dedication as world champion and ambassador for Puerto Rico. Thank you, Champ!"

According to the WBO, the Collazo-Matsumoto purse bids were scheduled for later on Monday in Puerto Rico. They have since been canceled due to Collazo's vacation.

In its announcement, the WBO confirmed that Matsumoto will be elevated to full champion. Matsumoto won the interim title by beating Russell Acosta Silveira by decision in September.

Although Collazo's move seemingly confirms his permanent weight change, he remains the WBA and The Ring minimumweight champion. It remains to be seen what he will do with either title in the coming months, though he will presumably vacate both before attempting another defense.

Oscar Collazo focusing on moving up

While many champions have vacated titles to move up before, Collazo was attempting to become a simultaneous two-division titleholder before leaving 105 pounds. He was initially scheduled to challenge WBC and WBA flyweight champion Ricardo Sandoval on Oct. 10 before withdrawing from the matchup late due to injury.

Sandoval instead accepted a fight against short-notice replacement Sergio Mendoza, who pulled off an incredible upset to steal the belts off his waist.

Still seemingly sidelined with his rib injury, Collazo remains without a definitive return timeline. 'El Pupilo' could feasibly challenge Mendoza in his next outing, with Masamichi Yabuki (IBF) or Anthony Olascuaga (WBO) also holding flyweight titles. The WBO's support of Collazo's vacating the minimumweight title could push him toward an immediate title shot against Olascuaga.

Collazo, who was recently replaced in the Ring Magazine top-10 pound-for-pound list by O'Shaquie Foster, appears content to remain at 112 pounds for the time being, but dominant fighters in the small weight divisions have historically moved up quickly to collect more belts. The Mexican superstar hinted that his next fight would come in January or February 2027.