John Riel Reponte Casimero (born February 13, 1989) is a Filipino professional boxer and YouTuber. He has held world championships in three weight classes; including the IBF junior-flyweight title from 2012 to 2013; the IBF flyweight title in 2016; and the WBO bantamweight title from 2019 to 2022. Quadro Alas is Tagalog for four of a kind when translated, his moniker means Four Aces.

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.^[4] 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.^[5] Casimero successfully defended that title two bouts later against Ardin Diale, until he got the biggest break of his career.

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.^[6] This win can give Casimero a title shot against Iván Calderón of Puerto Rico, who previously defeated Filipino boxer Rodel Mayol.^[7]

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.

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.^[8] He was, however, stopped by the South African in five rounds, therefore marking his second career loss.^[9]

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 interim junior flyweight championship.^[10] After the riot, police escorted Casimero and his team to their hotel and provided protection for them. Lazarte later visited to apologize.^[10] The Philippines has filed a diplomatic protest to the Argentine government after Argentine fans attacked Casimero in the ring after winning the title bout.^[10][11] Philippine Foreign Affairs spokesman Raul Hernandez stated that the Philippine Embassy in Buenos Aires filed a protest with Argentina's Ministry of Foreign Affairs and is awaiting an explanation.^[10] Lazarte was banned by IBF for threat, sparking a ring riot.^[11]

On July 19, 2012, Casimero was upgraded to the status of full IBF junior flyweight champion because of the inability of Ulises Solis to defend his title on or before October 30.^[12]

On his first defense of the IBF junior flyweight title, Casimero faced Pedro Guevara of Mexico on August 4, 2012. He scored a knockdown in the opening round and fought to a split decision victory.^[13]

He successfully made a second defense of his title against WBC Latino light flyweight champion Luis Alberto Rios on March 16, 2013.^[14] His third defense was against Felipe Salguero on October 26, 2013, and he won by eleventh-round knockout.^[15]

Following his win against Mauricio Fuentes and Armando Santos, Casimero moved back up to the flyweight division. On June 27, 2015, he lost his return to flyweight bout via unanimous decision against IBF champion Amnat Ruenroeng in a controversial match.^[16] A rematch on May 25, 2016, Casimero challenged Ruenroeng again for the IBF flyweight title and this time he knocked Ruenreong out with a vicious left hook to the body in the fourth round to become a two-division world champion.^[17]

In his second title defence, Casimero faced undefeated Charlie Edwards, on September 10, 2016, on the undercard of Gennady Golovkin vs. Kell Brook at The O2 Arena in London, England. Casimero was on the offensive for most of the fight, as Edwards was unable to deal with Casimero's ring craft. Casimero upped the pace in the tenth round, and dropped Edwards with a left hook. Edwards beat the count, but as soon as he got up, Casimero unleashed a flurry of punches towards the challenger, which prompted the referee to end the fight immediately.^[18]

On September 16, 2017, Casimero faced Jonas Sultan for IBF title eliminator. He lost via 12-round unanimous decision.^[19]

Following Casimero's successful title defense against Charlie Edwards in September 2016, he moved up in weight, fighting in non-title bouts at super-flyweight, bantamweight and even one bout against Jose Pech at featherweight before settling at the bantamweight division,^[20] where he defeated Ricardo Espinoza Franco via twelfth-round knockout to win the WBO interim bantamweight title in his first fight in the United States on April 20, 2019.^[21] He defended the interim title on August 24, 2019, against Cesar Ramirez, winning via tenth-round knockout, to become full WBO bantamweight titleholder Zolani Tete's mandatory challenger, setting up a showdown with Tete.^[22]

On 30 November 2019, Casimero challenged Zolani Tete for his WBO bantamweight title in Birmingham, England. Despite Tete being the favorite for the fight, Casimero scored a third-round knockout over the long-reigning champion to capture his WBO bantamweight title. The victory meant that Casimero became a three-division world champion.^[23]

Casimero have scheduled to face undefeated unified bantamweight champion Naoya Inoue in a unification clash on April 25, 2020, but the COVID-19 pandemic caused the fight to be cancelled.^[24] He instead faced the undefeated Duke Micah, ranked #11 by the WBO, in his first WBO bantamweight title defense on September 26, 2020, on the undercard of The Charlos vs. Dereyvanchenko and Rosario. Casimero recorded another stoppage win, again in the third round, to retain his WBO belt.^[25]

It was announced on June 19, 2021, that WBC champion Nonito Donaire would replace Rigondeaux,^[26] but when the fight between Casimero and Donaire fell apart over insults directed at Donaire's wife,^[27] Rigondeaux stepped back in to fight Casimero as had been originally planned.^[28] Casimero faced two-time Olympic gold medalist Guillermo Rigondeaux on August 14, 2021.^[29] In a low-key affair that saw the CompuBox record broken for fewest combined landed punches in a 12-round fight, Casimero pressured his opponent all night, fighting on the front foot and throwing more punches than Rigondeaux, who was reluctant to engage. Casimero was rewarded with a split decision victory, with scores of 117–111 and 116–112 in his favor, and 115–113 in favor of Rigondeaux.^[30]

In his post-fight interview, Casimero criticized his opponent's extremely passive gameplan, saying "I'm focused on [the] knockout, but Rigondeaux always runs. Rigondeaux just always runs. No fighting." He continued by reaffirming that it is his intention to unify the bantamweight division, targeting the division's other titleholders, Nonito Donaire and Naoya Inoue. Casimero concluded his interview by issuing the middle finger to Inoue.^[31]

Casimero had been scheduled to fight his mandatory challenger and former IBF bantamweight champion Paul Butler on December 11, 2021, at Coca-Cola Arena in Dubai, United Arab Emirates. Casimero withdrew before the weigh-ins after being rushed to the hospital due to viral gastritis.^[32] The bout had been rescheduled on April 22, 2022, at M&S Bank Arena in Liverpool, England but Casimero was not permitted to fight by the British Boxing Board of Control (BBBofC) due to medical guidelines violation by using a sauna to cut weight "in close proximity" to the fight.^[33][34] Casimero's late replacement, fellow Filipino Jonas Sultan, lost to Butler by unanimous decision, making Butler the interim champion.^[35] On May 4, the WBO stripped Casimero of the title, with Butler supplanting him.^[36]

On December 3, 2022, Casimero fought Japan's Ryo Akaho in a match in South Korea that was initially ruled a no contest before being revised to a knockout in favor of Casimero by the Korean Boxing Member Commission (KBM), which reviewed the matter upon the Games and Amusements Board's appeal. Later on, Casimero officially signed a contract under Treasure Boxing Promotion with the Japanese startup led by former world champion and CEO Masayuki Ito in February 2023.^[37] Casimero made a successful homecoming, dethroning Namibia's Fillipus Nghitumbwa via unanimous decision win to claim the WBO Global super bantamweight title at the Okada Manila in Paranaque City on May 13, 2023.^[38]

Casimero made his debut in Japan by taking on former IBF super bantamweight champion Yukinori Oguni on October 12, 2023, at the Ariake Arena in Tokyo, Japan. The bout ended with a Controversial Technical Draw because of an accidental headbutt.^[39] On October 13, 2024, Casimero won the super bantamweight match after defeating Saul Sanchez via knockout on the first round in Yokohama.^[40] On October 15, he was suspended by the Japan Boxing Commission for one year after he had exceeded the 122-pound weight-in limit prior to the match on October 12.^[41]

Major world titles:

• IBF light flyweight champion (108 lbs)
• IBF flyweight champion (112 lbs)
• WBO bantamweight champion (118 lbs)

Interim titles:

• WBO interim light flyweight champion (108 lbs)
• IBF interim light flyweight champion (108 lbs)
• WBO interim bantamweight champion (118 lbs)

Regional titles:

• PBF flyweight champion (112 lbs)
• WBO Asia Pacific light flyweight champion (108 lbs)
• WBO Global super bantamweight champion (122 lbs)

• 2024 1st Pacquiao-Elorde Awards Night
• 2023 Gabriel "Flash" Elorde Memorial Boxing Awards "Boxer of the Year" (for 2021)^[43]
• 2010 28th SAC-SMB Sportswriters Association of Cebu Sports Awards

In 2022, Casimero was charged with acts of lasciviousness and sexual assault over the alleged molestation of a 17-year-old whom he had invited to his hotel room in Taguig in June 2021.^[44] Casimero's brother and trainer, Jayson, called the charges “fabricated”.^[45]

Casimero has two daughters from a previous relationship.^[46][47]

Casimero has a YouTube channel called Quadro alas tv vlog. Casimero also had a channel called Quadro Alas it's my boy but is now mainly managed by his brother and trainer, Jayson, since late 2021.^[48]

On August 20, 2021, Vloggers TV announced that Casimero will be fighting in the first Battle of the YouTubers Season 2 celebrity boxing card.^[49] It was announced on December 22, 2021, that Casimero will be facing Jormiel Labador in the supporting bout scheduled on December 28, 2021, in Metro Manila, Philippines.^[50][51] However, Casimero was forced to pull out of the exhibition matched after the WBO prohibited Casimero from partaking in any event negotiations without the authorization of the sanctioning body and Probellum—the promoter of the card that was supposed to be topped by the postponed title defense against Paul Butler on December 11, 2021.^[52] Casimero was replaced by his brother and trainer, Jayson, in the exhibition bout and won.^[53]

• List of world light-flyweight boxing champions
• List of world flyweight boxing champions
• List of world bantamweight boxing champions
• List of Filipino boxing world champions
• List of boxing triple champions

• Boxing record for John Riel Casimero from BoxRec (registration required)
• John Riel Casimero - Profile, News Archive & Current Rankings at Box.Live