Johnriel Casimero

Following his win against Mauricio Fuentes and Armando Santos, Casimero moved back up to the flyweight division. On June 27, 2015, Casimero lost his return to flyweight bout via unanimous decision against IBF flyweight champion Amnat Ruenroeng in a controversial match. On May 25, 2016, Casimero challenged Ruenroeng again for the IBF flyweight title and knocked him out with a vicious body shot in the 4th round.

He successfully made a second defense of his title against WBC Latino light flyweight champion Luis Alberto Rios on March 16, 2013. His third defense was against Felipe Salguero on October 26, 2013 and he won by eleventh-round knockout.

On February 11, 2012, Casimero, and members of his team were kicked and assaulted when fans in Mar Del Plata hurled chairs and stormed the ring following his 10th-round knockout of local Argentine fighter Luis Alberto Lazarte for the IBF junior flyweight championship.

On July 19, 2012, Casimero was declared as the regular IBF Junior Flyweight World Champion because of the inability of Ulises Solis to defend his title on or before October 30.

On his first defense of the IBF junior flyweight title, Casimero faced Pedro Guevarra of Mexico on August 4, 2012. He scored a knockdown in the opening round and fought to a split decision victory.

Casimero got his first shot at a world title when he challenged Moruti Mthalane of South Africa for the IBF flyweight title on March 26, 2011. He was, however, stopped by the South African in five rounds, therefore marking his second career loss.

This win can give Casimero a title shot against Iván Calderón of Puerto Rico, who previously defeated Filipino boxer Rodel Mayol. Casimero fought Ramón García Hirales on July 3, 2010, for his first defense of the interim WBO light flyweight title but lost by split decision.

On December 19, 2009, in Managua, Nicaragua, Casimero won the then vacant interim WBO light flyweight title, by defeating former interim WBA Light Flyweight champion César Canchila of Colombia. Canchila had a record of 28–2 coming into the bout, with his last loss coming from current WBA Light Flyweight World Champion Giovanni Segura, whom he previously defeated for the interim title. Casimero gave a spectacular performance, the fight being his first outside his home country. He was able to knockdown Canchila multiple times until the referee finally stopped the bout in the 11th round of the scheduled 12 round interim title fight.

On August 23, 2008, just a year after turning pro, Casimero defeated Rodel Quilaton for the then vacant Philippines Boxing Federeration (PBF) Flyweight title, winning a unanimous decision (UD) through ten rounds. Following the bout, Casimero moved down one division, to light flyweight, defeating Liempetch Sor Veerapol of Thailand by technical knockout (TKO) in the fifth round to claim the then vacant WBO Asia Pacific Light Flyweight title. Casimero successfully defended that title two bouts later against Ardin Diale, until he got the biggest break of his career.

John Riel Casimero (born February 13, 1990 in Ormoc, Leyte, Philippines), more commonly known as Johnriel Casimero, is a Filipino professional boxer. He is a three-weight world champion, having held the WBO bantamweight title since November 2019 and previously, the IBF junior-flyweight title from 2012 to 2013 and the IBF flyweight title in 2016, as well as the WBO interim junior-flyweight title from 2009 to 2010 and WBO interim bantamweight title in 2019. Quadro Alas is Tagalog for four of a kind when translated, his moniker means Four Aces.