Former three-division champion Abner Mares was forced to pull out of his Feb. 9 main event against WBA junior lightweight champion Gervonta Davis with a right elbow injury suffered in training, Showtime announced on Wednesday. 

Davis (20-0, 19 KOs) has agreed to defend his title against replacement and former 122-pound titleholder Hugo Ruiz (39-4, 33 KOs). The bout will headline a Premier Boxing Champions triple-header at Dignity Health Sports Park in Carson, California (formerly the StubHub Center).

Ruiz, 30, a native of Mexico, accepted the fight just 11 days removed from his decision win over Alberto Guevara on the Manny Pacquiao-Adrien Broner Showtime pay-per-view card in Las Vegas. Guevara was a last-minute replacement for interim WBA featherweight titleholder Jhack Thepora, who missed weight and was stripped of his title. 

The 33-year-old Mares (31-3-1), who was moving up in weight to contend for his fifth world title in four divisions, was frustrated by the decision to withdraw. 

"I'm not going to sugarcoat this. I'm disappointed and devastated that I've injured my right elbow in sparring," Mares said. "This is something that I haven't had happen to me during my career and the feeling is just horrible. I will be going to see my doctor about this and am prepared to follow whatever recommendations and rehab that gets me back into the ring. I'm healthy, not afraid of doing the work and I will be back. This is a temporary setback. Don't count me out."

Although he is smaller in size, Mares was expected to be the toughest challenge of Davis' career. "Tank," a 24-year-old native of Baltimore who is promoted by Floyd Mayweather and has been routinely touted as the future of the sport, knocked out Jesus Cuellar last April in his only appearance during a year that was marred by personal issues and differences with Mayweather.

"I trained for three months to fight a southpaw when I fought in January," Ruiz said. "When the opponent changed, it was hard to adjust in 24 hours. After the fight I immediately went back to the gym, because you never know what's going to happen in boxing. I'm 100 percent ready to knock out Gervonta Davis."

Although he's moving up in weight to face Davis, the brawling Ruiz will enter with a four-inch height advantage and fresh off a three-fight win streak. He is best known for being stopped by Julio Ceja in their WBC junior featherweight war in 2015 only to gain redemption via knockout in their rematch. 

The Showtime triple-header will also include unbeaten junior welterweight Mario Barrios against Richard Zamoa. Former world champion Javier Fortuna will face powerful lightweight contender Sharif Bogere.