Donnie Nietes has officially vacated his WBO super flyweight world title.

The four-division champion wrote a letter to WBO President Francisco Valcarcel stating his intent on relinquishing the world title that he won on December 31, 2018, ending his reign without a single title defense.

The news comes on the day that a purse bid between Nietes and mandatory challenger Aston Palicte was scheduled to take place in Puerto Rico. Instead of the news of who won the purse bid, the WBO revealed that its 115-pound world title is now vacant.

The letter written by Nietes, which can be seen in the tweet below, stated that one of the reasons for him vacating the title was that he wants a career-defining fight that would cement his legacy. Nietes believes that at 37 years old, he does not have much time remaining in his career to get that kind of fight.

BREAKING: Donnie Nietes has vacated the WBO super flyweight title. In a letter to WBO president Francisco Valcarcel, Nietes vacated the belt because he wants a “career defining fight” and he does not have much time left in his career before he retires. Below is Nietes’ letter. pic.twitter.com/abc45bKAPH — Carlos Toro (@CarlosToro360) February 28, 2019

A second letter, penned by ALA Promotions President and CEO Michael Aldeguer, echoes Nietes’ sentiments about vacating his title and added that a mandatory rematch against countryman Aston Palicte “is an emotional and mental challenge” after the two fought to a draw last year. The two boxers competed for the belt previously held by Naoya Inoue last September, but since the fight ended as a draw, the title remained vacant.

A second letter, penned by ALA Promotions CEO Michael Aldeguer, echoes Nietes’ sentiments about vacating his title and added that a mandatory rematch against countryman Aston Palicte “is an emotional and mental challenge” after the two fought to a draw last year. pic.twitter.com/oskUeM7iAv — Carlos Toro (@CarlosToro360) February 28, 2019

The WBO announced several weeks later after the September bout that Nietes would fight Kazuto Ioka on December 31 in Macau, China to crown a new champion while Palicte would fight Jose Martinez in a title eliminator. Nietes defeated Ioka by split decision to win the WBO super flyweight title while Palicte stopped Martinez in two rounds on January 31 on a boxing card streamed on UFC Fight Pass.

As for what’s next for the WBO 115-pound title, the organization typically orders its two highest-ranked available contenders to fight for the title, meaning it’s likely that Palicte will be ordered to fight Ioka, ranked No. 4 by the organization. Juan Francisco Estrada, ranked No. 2, will fight for the WBC title on April 26 and third-ranked Ryuichi Funai is likely fighting for the IBF title, held by Jerwin Ancajas, but that fight has not been announced.

Nietes has won a plethora of titles across several weight classes, including the WBO title at minimumweight, light flyweight and super flyweight as well as the IBF belt at flyweight.