Former unified featherweight champion Yuriorkis "El Ciclon de Guantanamo" Gamboa (27-2, 17 KOs) will step in to fight Jason "El Canito" Sosa (20-2-4, 15 KOs) in a 10-round super featherweight fight at the Theater at Madison Square Garden in the televised opener to Kovalev vs. Shabrankskyy. The event takes place Saturday, Nov. 25 and will be televised live on HBO World Championship Boxing beginning at 10:00 p.m. ET/PT.

Gamboa, a 35-year-old native of Guantanamo, Cuba, is an Olympic Gold Medalist who shot to the top of the Featherweight rankings to win two world titles, defeating the likes of Orlando "Siri" Salido and Daniel Ponce De Leon before officially moving up to 130 pounds. Gamboa has also faced stiff competition as a super featherweight, with wins against Darleys Perez and Rene "El Gemelo" Alvarado under his belt. Gamboa is replacing Robinson "Robin Hood" Castellanos, who pulled out of this fight due to an injury.

"I'm excited for this great opportunity to fight Sosa on the undercard of Kovalev-Shabranakssy," said Gamboa. "A win over Sosa on HBO could push me back into title contention. I'm a fighter with many aspects and dimensions, and that's what I'll bring in my fight against Sosa. For my my last fight, I wasn't prepared well. This time I will be very much prepared, so I can walk away with my hand raised."

"I'm excited for Gamboa," said Zeferino Ramirez of ZR Entertainment. "This is the fight we wanted. And I expect big things in 2018. He'll be ready for any 130-pound champion if he is successful on November 25."

The 29-year-old Sosa, of Camden, NJ, is the former WBA World Super Featherweight Champion. He earned his title by handing Javier "El Abejon" Fortuna his first loss as a pro with an 11th-round knockout in Beijing, China in June 2016. Sosa successfully defended his title with a 12-round decision win over Stephen Smith in Monte Carlo in November 2016 before returning several months later in a tough fight against Vasyl "Hi-Tech" Lomachenko in April 2017. Sosa is also known for fighting to an impressive majority draw against former WBA Super World Featherweight Champion Nicholas "Axe Man" Walters and for stopping former world title challenger Jerry "The Corpus Christi Kid" Belmontes in only one round.

"People think we have an easier opponent in Gamboa since Castellanos beat him, but we're not buying into that," said Sosa.  "Maybe Gamboa didn't take Castellanos seriously.  We expect to see the very best Gamboa on Nov. 25.  Having said that, this is not about who we are fighting; this is about why.  We are fighting to make Puerto Rico proud after what all the people who live there have been through recently."

"This should be a solid fight between two guys, the same size, who like to hurt people," said Russell Peltz, Hall of Fame Promoter of Peltz Boxing Promotions."It's a better matchup, style-wise, than the one between Jason [Sosa] and Robinson Castellanos."

Kovalev vs. Shabranskyy is a 12-round fight for the vacant WBO Light Heavyweight World Title promoted by Main Events and Krusher Promotions in association with Golden Boy Promotions. Barrera vs. Valera is a 10-round light heavyweight fight promoted by Main Events in Association with Shuan Boxing Promotions. Gamboa vs. Sosa is a 10-round super featherweight fight promoted by Golden Boy Promotions in association with Peltz Boxing and ZR Entertainment. The event will take place on Nov. 25 at the Theater at Madison Square Garden in New York City, and will be televised live on HBO World Championship Boxing beginning at 10 p.m. ET/PT.