Luis Alberto Lopez pulled off a career-changing upset Friday night.

The Mexican veteran beat up previously unbeaten junior lightweight prospect Gabriel Flores Jr. in the co-feature on Oscar Valdez-Robson Conceicao undercard in Tucson, Arizona. The relentless, rugged Lopez pressured Flores for most of their fight, hurt him several times, and bruised and bloodied his face on his way to winning a 10-round unanimous decision at Casino Del Sol’s AVA Amphitheater.

The 28-year-old Lopez (23-2, 12 KOs), of Mexicali, Mexico, has won six straight fights since then-unbeaten southpaw Ruben Villa out-pointed him in a 10-rounder in May 2019. The 21-year-old Flores, of Stockton, California, suffered his first professional defeat (20-1, 7 KOs) in a fight ESPN+ streamed.

Judges Federico Encinas (100-90), Steve Sandoval (100-90) and Roger Woods (98-92) all scored the fight for Lopez by wide distances.

Flores’ father repeatedly told his son in the corner that he wanted to stop the fight before the 10th round began, but the younger Flores talked his father into allowing him to continue.

Flores held and threw punches during the 10th round, but he unnecessarily took more punishment in those final three minutes as Lopez pressured him. The elder Flores tried to stop the action toward the end of the 10th round, but referee Robert Velez didn’t notice him attempting to stop the bout.

Flores connected with three straight jabs and a left hook with about 1:10 to go in the ninth round. None of those punches affected Lopez, though, and he continued to come forward.

With just under 30 seconds to go in the ninth round, Lopez blasted Flores with a left hook that hurt him badly. Flores bravely withstood that shot and Lopez’s ensuing onslaught, and made it to the bell that ended the ninth round.

A flush right uppercut by Lopez knocked Flores into the ropes with 2:07 to go in the eighth round. Lopez pressured Flores for the rest of that round and continued to land the harder shots with regularity.

Lopez’s four-punch combination, punctuated by his right hand, affected Flores 25 seconds into the seventh round and made him move away from a hard-charging Lopez. With 1:15 to go in the seventh round, Lopez landed a left to Flores’ body that hurt him.

Lopez pressured Flores thereafter and landed various punches to his head and body during the remainder of a completely one-sided seventh round.

A right-left combination by Lopez snapped back Flores’ head 25 seconds into the sixth round. Lopez landed a right hand on a retreating Flores 1:05 into the sixth round as well.

Flores landed a left hook and then backed away with 20 seconds on the clock in the sixth round.

Lopez connected with a right hand and then a left hand as Flores backed into the ropes a few seconds after the halfway mark of the fifth round.

Flores fought off his back foot throughout the fourth round, when his punch output waned. Lopez drilled Flores with a straight right hand a few seconds before the fourth round ended.

Lopez landed a left to Flores’ body that made him retreat about 1:10 into the third round. Flores clipped Lopez with a left hook to the head just after the midway point of the third round.

Flores caught Lopez with a short, left hook with just under 45 seconds on the clock in the third round.

Flores got good extension on a right hand that landed with about 1:35 to go in the second round. Lopez landed a right to the body and then a left downstairs just after the halfway point of the second round.

Flores connected with a left to the body with just under a minute remaining in the second round. He also landed a left hook up top a few seconds before the second round ended.

Lopez drilled Flores with a right hand about 30 seconds into their fight. He rocked Flores with a looping right hand with just over 50 seconds to go in the opening round.

Velez warned Flores for low blows twice in the final 1:15 of the first round.

Keith Idec is a senior writer/columnist for He can be reached on Twitter @Idecboxing.