John Riel Casimero handed Guillermo Rigondeaux his sunglasses Friday afternoon when Rigondeaux requested that Casimero take off his shades as they stood face-to-face.

Casimero promised to hand Rigondeaux a devastating defeat Saturday night that’ll send him into retirement, too.

The top bantamweights both met their contractual obligations for a 12-round main event Showtime will televise from Dignity Health Sports Park in Carson, California. The Philippines’ Casimero came in right at the bantamweight limit of 118 pounds, whereas Rigondeaux stepped on the California State Athletic Commission’s scale at 117½ pounds.

The 32-year-old Casimero (30-4, 21 KOs) will make the second defense of his WBO bantamweight championship against Rigondeaux (20-1, 13 KOs, 1 NC), a 40-year-old, Cuban-born southpaw.

The Casimero-Rigondeaux fight was one of the most intriguing bouts on the four-month schedule of fights Showtime announced late in April. Nonito Donaire replaced Rigondeaux as Casimero’s opponent, however, after Donaire won the WBC bantamweight title from France’s Nordine Oubaali by fourth-round knockout May 29 at Dignity Health Sports Park.

The Philippines’ Donaire (41-6, 27 KOs) withdrew from the Casimero clash soon thereafter, though, primarily because he and his wife/manager, Rachel Donaire, weren’t satisfied with Casimero’s enrollment in the Voluntary Anti-Doping Association’s testing program for performance-enhancing drugs.

Rigondeaux gladly stepped back in for Donaire, whom Rigondeaux defeated by unanimous decision in April 2019 at Radio City Music Hall in New York.

The four other fighters Showtime will showcase Saturday night made weight earlier Friday afternoon as well.

Gary Antonio Russell (18-0, 12 KOs), of Capitol Heights, Maryland, officially weighed 116¾ pounds for his 12-round bantamweight bout against Emmanuel Rodriguez (19-2, 12 KOs). Puerto Rico’s Rodriguez, a former IBF bantamweight champ, weighed in at 118 pounds for Showtime’s co-feature, which will be contested for the WBA’s interim 118-pound crown.

Rau’shee Warren (18-3, 4 KOs, 1 NC), a former IBO/WBA bantamweight champ from Cincinnati, stepped on the scale at 117½ pounds for his 10-round bout against Damien Vazquez (15-2-1, 8 KOs). Las Vegas’ Vazquez weighed 117¼ pounds for the opener of Showtime’s three-bout broadcast, set to begin at 10 p.m. EDT and 7 p.m. PDT.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.