On September 16, 2017, a 28-year-old John Riel Casimero (24-3, 15 KOs) and a 25-year-old fellow Filipino boxer Jonas Sultan (13-3, 8 KOs) met in the ring.
Casimero came in to the fight on a 3-fight win streak with a 55% KO rate, and was fighting after a gap of 2 months and 22 days. Sultan was on a 4-fight win streak with a 50% KO rate, and fighting after a layoff of 4 months and 9 days.
Jonas Sultan defeated John Riel Casimero via unanimous decision in the 12-round fight. Sultan improves his record to 14-3, while Casimero adds a loss to his record at 24-4.
On June 27, 2015, a 26-year-old John Riel Casimero (21-2, 13 KOs) got a shot at the flyweight IBF title held by 35-year-old Thai boxer Amnat Ruenroeng (15-0, 5 KOs).
Casimero came in to the fight on a 7-fight win streak with a 56% KO rate, and was fighting after a gap of 6 months and 14 days. Ruenroeng was on a 15-fight win streak with a 33% KO rate, and fighting after a layoff of 3 months and 19 days.
Amnat Ruenroeng defeated John Riel Casimero via unanimous decision and successfully defended his IBF flyweight title. Ruenroeng improves his record to 16-0, while Casimero adds a loss to his record at 21-3.
On March 26, 2011, a 22-year-old John Riel Casimero (14-1, 8 KOs) got a shot at the flyweight IBF title held by 28-year-old South African boxer Moruti Mthalane (26-2, 17 KOs).
Casimero came in to the fight on a 1-fight losing streak with a 53% KO rate, and was fighting after a gap of 8 months and 2 days. Mthalane was on a 3-fight win streak with a 60% KO rate, and fighting after a layoff of 6 months and 25 days.
Moruti Mthalane stopped Johnriel Casimero via TKO in the 5th round of the 12-round world-title fight, and successfully defended his IBF flyweight title. Mthalane improves his record to 27-2 (18 KOs), while Casimero adds a loss to his record at 14-2.
On July 24, 2010, a 21-year-old John Riel Casimero (14-0, 8 KOs) and Ramón García Hirales met in the ring in a light-flyweight bout.
Casimero came in to the fight on a 14-fight win streak with a 57% KO rate, and was fighting after a gap of 7 months and 5 days.
John Riel Casimero lost to Ramón García Hirales via split decision in the 12-round light-flyweight fight, and adds an loss to his record at 14-1.