WBC junior lightweight world titlist Oscar Valdez defends his belt against Robson Conceicao on Friday (ESPN+, 10 p.m. ET, with undercard fights starting at 6:10 p.m. ET) in Tucson, Arizona.

Valdez tested positive for the banned substance phentermine in August, but the Pascua Yaqui Tribe Athletic Commission allowed Valdez to fight at the Casino Del Sol. The WBC decided not to strip Valdez of his title, stating that “this is not a performance-enhancing drug” and that “Valdez will have absolutely no advantage and the challenger will have no risk.”

Valdez (29-0, 23 KOs), 30, of Nogales, Sonora, Mexico, won the title by defeating Miguel Berchelt by a 10th-round TKO in February in a great performance.

Conceicao (16-0, 8 KOs), 32, of Salvador, Bahia, Brazil, has won three of his past five fights by stoppage, including a seventh-round TKO victory over Jesus Antonio Ahumada in April.

Also on the card, WBO flyweight champion Junto Nakatani (21-0, 16 KOs), 23, of Inabe-gun, Mie, Japan, faces power puncher Angel Acosta (22-2, 21 KOs), 30, of San Juan, Puerto Rico, in a 12-round battle.

Stay here for live undercard results and analysis.

Fight in progress: Oscar Valdez vs. Robson Conceicao, 12 rounds, for Valdez’s WBC junior lightweight title

Round 3: Valdez landed a big right at the beginning of the round, but Conceicao fired back and went back to work, connecting on plenty of 1-2s that kept Valdez at the end of his jab. 10-9, Conceicao. 30-27, Conceicao.

Round 2: Conceicao in total control through two, but it’s still early. Very patient approach, yet aggressive. Firing right hands through the guard and Valdez’s face is already swelling and red. 10-9, Conceicao. 20-18, Conceicao.

Round 1: Conceicao connects on a bundle of right hands to the body and did a really nice job controlling range, using his superior height and reach. 10-9, Conceicao.

Results:

Lopez dominates, upsets Flores

Luis Alberto Lopez scored the upset against Gabriel Flores Jr. in the 10-round co-feature, a shellacking from bell to bell of the undefeated prospect — and a 13-1 favorite. All three judges scored the fight for Lopez: 98-92, 100-90 and 100-90.

Lopez (23-2, 12 KOs) was relentless and continued to march Flores down round after round. Before the 10th and final round, Flores’ trainer and father, Gabriel Flores Sr., informed his son he was stopping the fight. The 130-pounder pleaded and pleaded; his father acquiesced. With about 10 seconds left in the round, with Flores absorbing more and more punishment, Flores Sr. informed the commission supervisor to stop the fight, but the referee never saw him on the apron.

“I really was expecting the fight to be stopped; I was looking at the referee,” Lopez said through an interpreter.

Flores’ left eye was badly swollen from the abundance of power shots delivered with nonstop pressure. He had no answers and was shut out on two of the three cards.

“He f—ing embarrassed me,” an emotional Flores said, his face badly marked up. “He was f—ing my body up. I’m very disappointed in myself. No excuses. No one wants to know what happened. Either you won or you lost.”

The 21-year-old from Stockton has been built up slowly by Top Rank, but where he goes from here is unclear. Flores (20-1, 7 KOs) was coming off a sixth-round TKO of Jayson Velez.

Lopez connected on 142 power punches to just 68 from Flores. Lopez, 28, of Mexico, a natural 126-pounder, also owns a victory over Andy Vences.

Nakatani retains title with TKO victory

Junto Nakatani, ESPN’s No. 3 flyweight, retained his title with a fourth-round TKO of Angel Acosta. The fight was halted on the advice of the ringside doctor after Acosta suffered an apparent broken nose in Round 2. The blood poured into his mouth, but Acosta pressed on. He even stunned the champion toward the end of Round 2.

But Nakatani kept delivering punches to the nose, creating more and more blood that sprayed everywhere in the ring. Acosta fought bravely, but his title bid was finally stopped at 32 seconds of Round 4.

“I caught him in the first round right in the nose,” Nakatani said through an interpreter. “… I knew [it was broken]. … I want to unify the titles.”

Nakatani (22-0, 17 KOs) was fighting for just the first time outside his native Japan. The 23-year-old was making the first defense of the 112-pound title he won in November with an eight-round KO of Giemel Magramo.

Acosta (22-3, 21 KOs) was a champion at 108 pounds and made three successful defenses before suffering a 12th-round KO to Elwin Soto in June 2019. The 30-year-old Puerto Rican is ranked No. 9 by ESPN at 112 pounds.

Zayas wins but doesn’t shine against Sanchez

Xander Zayas remained unbeaten in his first fight at junior middleweight but proved he still has much to learn.

The 19-year-old Puerto Rican defeated Jose Luis Sanchez via unanimous decision — 60-53, 60-54 and 60-53 — in his toughest test to date and laid a sustained beating for most of the six-round fight, but he also showed some flaws that need to be fixed in the gym.

Zayas (10-0, 7 KOs) was an offensive machine and showed good punch variety and aggression, but he also received his fair share of shots throughout the fight. In Round 3, Zayas connected with a big left hook that floored Sanchez, but the referee missed the knockdown.

“The heat got to me a little bit in the later rounds,” Zayas said after the fight. “We knew it would be hot here in Arizona. We also knew that Sanchez was a tough opponent. He comes from a tough fighting family, and he’s a proud Mexican warrior. I knew he was coming to fight. We did the job, I listened to my corner, boxed him, and got the unanimous decision. That’s the most important thing.”

Sanchez (11-2-1, 4 KOs) was coming off a draw with former title challenger Adrian Granados. The 28-year-old native of Albuquerque, New Mexico, was bleeding profusely by the end of the fight.

Delgado demolishes Zamudio in two rounds

Lindolfo Delgado, a 2016 Olympian, scored a second-round stoppage of Miguel Zamudio to improve to 13-0 (12 KOs).

The 26-year-old Mexican laid a beating on Zamudio from the opening bell and scored a knockdown in Round 2 with a right hand. Zamudio (45-18-1, 28 KOs) beat the count but was stopped on his feet 50 seconds into the round.

Zamudio, 30, has won just one bout in his past six fights. Delgado, a 140-pound prospect, signed with Top Rank earlier this year.

Giron scores late KO over Garza

Rene Tellez Giron broke down Eduardo Garza before scoring a knockout in Round 7, the result of a brutal left hook to the body.

Giron (16-1, 10 KOs) delivered a short right uppercut, a throwaway punch meant to bring Garza’s hands down, before slipping the liver shot in, sending Garza to the mat in agony. The 22-year-old Mexican fighter scored a shocking upset of Carlos Balderas in 2019 on the heels of his first professional defeat earlier that year, a unanimous-decision loss to impressive prospect Michel Rivera. Suddenly, Giron is a fighter to watch at 130 pounds.

Garza (15-5-1, 8 KOs), a 32-year-old native of Dover, Delaware, has now lost three straight.

Aguilar stops Portillo to stay unbeaten

Omar Aguilar, 22, improved to 22-0 (21 KOs) with a second-round KO of Carlos Manuel Portillo. The lanky 140-pounder scored a knockdown in the closing seconds of Round 1 and then finished him off with two more knockdowns in the opening moments of the second round.

Following the third knockdown, Portillo was favoring his right eye while on the canvas as the ref reached the count of 10. A compact left uppercut inflicted the damage on the eye and gained Aguilar the win in his first fight outside of his native Mexico.

Portillo (22-4, 17 KOs), 28, a native of Paraguay, lost for the fourth time in his past five fights.

ESPN Boxing