The Mexican southpaw dropped Ricardo Sandoval three times and knocked out the heavily favored WBA/WBC flyweight champion in the fifth round of their scheduled 12-round, 112-pound championship clash at DePaul University’s Wintrust Arena in Chicago. Sandoval stepped into the ring as DraftKings’ 7-1 favorite over Mendoza, who replaced Oscar Collazo as Sandoval’s opponent on approximately three weeks’ notice.

DAZN streamed Mendoza’s dramatic upset as the co-feature before Floyd Schofield Jr. and Lucas Bahdi fought for the vacant WBA lightweight title in the main event.

“I’m gonna dedicate this incredible win to my brother that just passed away,” a crying Mendoza told DAZN broadcasters Chris Mannix and Sergio Mora during his post-fight interview. “But the emotions that are going through me [are] incredible. But all the hard work finally paid off.”

Mendoza (28-1, 24 KOs) was knocked out in the second round of his previous bout by IBF junior flyweight champ Thanongsak Simsri (41-1, 36 KOs) on April 13 at Korakuen Hall in Tokyo. You wouldn’t have known it by the way the 5-foot-8 southpaw dismantled Sandoval (27-3, 18 KOs), who was knocked out for the first time in his 10-year, 30-fight pro career.

“I would say that I’m not a natural 108-pounder,” Mendoza said regarding his loss to Simsri. “I’m a natural 112-pounder and I sacrificed and that’s what cost me in that fight. But now, I’m a 112-pounder and everyone saw it.”

Mendoza dropped Sandoval twice in the second round and once in the fifth. Sandoval got up quickly from all three knockdowns, but referee Mark Nelson halted the action at 1:46 of the fifth because the former champion was under attack and still hurt from the third knockdown.

A counter right hook by Mendoza sent Sandoval down to his gloves and one knee with 1:40 to go in the fifth.

A right hook to the top of Sandoval’s head produced the first knockdown of their bout, with 1:39 on the clock in the second round. A vicious left uppercut dropped the Rialto, California resident again with 18 seconds to go in the second.

Sandoval ignored instructions in the third and fourth rounds, yet he managed to make their fight competitive again. He ultimately couldn’t withstand Mendoza’s power, which might make Collazo reluctant to fight the newly crowned champ.

Puerto Rico’s Collazo (15-0, 12 KOs), The Ring and WBO 105-pound champion, withdrew from his shot at Sandoval’s titles last month after suffering a rib injury in training.

Jahmal Harvey demonstrated some of the skill, speed and power on the undercard that have made him a top prospect.

The 2024 U.S. Olympian switched stances and had his way with Pedro Castaneda until he drilled his opponent with a left hand that knocked Castaneda flat on his back 54 seconds into the third round.

Castaneda got up before referee Dave Smith counted to 10. Smith still didn’t like the look in the Mexican’s eyes and stopped their scheduled eight-rounder at 1:08 of the third.

The 23-year-old Harvey, of Oxon Hill, Maryland, improved to 5-0 and recorded his fourth knockout. Castaneda (9-2-1, 5 KOs), who had not been knocked down before Saturday night, also lost inside the distance for the first time in his seven-year pro career.

“I didn’t even throw [that punch] to knock him out,” Harvey told DAZN's Chris Mannix in the ring. “I threw it as a setup. I was kinda shocked it landed. I was trying to run him into my right hook, so I threw the left as a decoy. But it knocked him out.”

Puerto Rican junior lightweight Jan Paul Rivera remained unbeaten by dominating Mexico’s Abraham Perfecto in the 10-round bout before Harvey’s victory.

Rivera (17-0, 7 KOs) dropped Perfecto (14-3, 9 KOs) with a counter left hook in the second round, buzzed him with another left hook in the ninth and won by the identical score of 99-89 on the cards of judges Caroline Burgess, Cassandra Lewis and Andrew Thorp. Though Rivera won every round and scored a knockdown, he won by 10 points, not 11, because referee Tommy Gonzalez deducted a point from him for a low blow in the ninth.

Joshua Edwards (8-0, 7 KOs) def. Craig Lewis (15-10-1, 8 KOs) TKO2 – heavyweights

Grant Flores (14-0, 10 KOs) def. Mikey Dahlman (19-3, 17 KOs) TKO2 – junior middleweights

Naomy Valle (16-1, 9 KOs) def. Shayla Moreno (5-2-1, 1 KO) UD8 (78-72, 78-73, 77-74) – strawweights