Continuing to honor its pledge to make competitive fights, Golden Boy Boxing on ESPN delivered two significant upsets in the main and co-main events on Cinco De Mayo, with lightweight Robinson "Robin Hood" Castellanos (22-11, 14 KOs) taking out Yuriorkis "El Ciclon de Guantánamo" Gamboa (26-2, 17 KOs) in the main event and Jesus Rojas (25-1-2, 18 KOs) claiming the WBA-NABA featherweight title from Abraham "El Chamaco" Lopez (22-1-1, 15 KOs) in the co-main.

In the main event scheduled for 10 rounds, Gamboa - a former Olympic medalist and two-time world champion - tasted the canvas in the second and fourth rounds before declining to come out of his corner for the eighth round, giving Castellanos the TKO victory.

"I am super happy and excited to get such a big win," Castellanos said. "I won against a revered Olympian, and this win puts my career back on track after my last fight. This win is the opportunity that I needed, and it's because of the incredible team around me."

"I felt super dizzy, and felt like I couldn't go on," said Gamboa. "We trained hard."

In the co-main event, Rojas from Caguas, Puerto Rico wrested the WBA-NABA featherweight title from Lopez of La Puente, CA. Rojas dropped Lopez three times over the course of the fight before the referee stopped the fight in the eighth round, giving Rojas the TKO victory.

"It's almost three years since I've fought in the U.S.; this win is the opportunity to be on the global stage, and take on world champions," Rojas said. "I promised my father that I would become a world champion, and even though he is not with me any more, I carry on our dream. I hope that by the end of the year, I am competing for an interim title or even a world championship."

"It's tough to swallow, I'm still processing it, but it happens," Lopez said. "After this, I know I'm going to go back to the drawing board and start training hard again."

Making his television debut, white-hot lightweight prospect Vergil Ortiz, Jr. (5-0, 5 KOs) out of Dallas, Texas went past the first round for the first time, but put Durango, Mexico's Angel "Pescado" Sarinana (7-6-2, 3 KOs) down in the third round with a savage right uppercut, and the referee ruled that Sarinana could no longer continue.

"I saw him get hurt in the first round when hit him in the body with a hook," Ortiz said. "Since that moment, I was just looking for the opportunity to get the knock out, but he was a tough guy and was able to make it through. In the third round, I saw him lose he guard, and I landed my uppercut that sent him to the floor. I think after this, I'm ready to increase my rounds. I think I am ready to take on some tougher opponents."