The Puerto Rican had been told by the sanctioning body he had to face interim champion Ryusei Matsumoto, with a November 2 deadline to agree terms.

Hours before their proposed fight went to purse bids, the 29-year-old champion decided to notify them he was vacating the belt. Matsumoto (9-0, 4 KOs) has subsequently been elevated to full titleholder, having outpointed Russell Acosta for the interim belt on September 27.

Collazo (15-0, 12 KOs) had been due to jump two weight classes, facing then unified flyweight champion Ricardo Sandoval on October 10 before a rib injury curtailed those plans.

Sandoval fought late substitute Sergio Mendoza, who dropped the defending champion in the second round before a shocking fifth-round stoppage to produce one of the year's great upsets.

Collazo still holds the Ring and WBA titles, while Takeshi Ishii (12-1, 9 KOs) holds the WBA secondary belt and will defend that distinction against Zyvyr John Medecilo (9-0, 5 KOs) on November 26.

It remains to be seen if Collazo will also vacate his WBA crown and still commit to moving up in weight, having seriously considered the possibility before injury.

He has previously suggested an unwillingness to move up to 108 pounds, given his friend and countryman Rene Santiago holds WBA/WBO titles and will look in a different direction.

The Ring reached out for comment from Team Collazo but hadn't heard back at the time of posting this story.