ARLINGTON, Texas – Miguel Flores felt this was a fight he had to take on short notice.

The featherweight contender was already training to face a southpaw. And this was a WBA world featherweight championship elimination match.

A victory would’ve moved him toward another title shot, this time in the featherweight division in which he is more comfortable.

Flores figured the risk was worth the reward, but Ramirez made him regret that decision Saturday night.

Mexico’s Ramirez knocked out Flores with a crushing counter right hook early in the fifth round of their scheduled 12-rounder on the Errol Spence Jr.-Danny Garcia undercard at AT&T Stadium. Flores (24-4, 12 KOs) got up from that shocking shot, but he stumbled and referee Laurence Cole quickly determined Flores shouldn’t continue just 20 seconds into the fifth round.

Cole also was the referee when Flores’ older brother, Benjamin Flores, lost by eighth-round technical knockout to Al Seeger in April 2009 in Dallas. Benjamin Flores, 24, died five days later from brain damage suffered during that bout.

This had been an emotional week for Miguel Flores, because he spent all week in Dallas. The hotel where Benjamin Flores’ fatal fight took place is right across the highway from the host hotel for Spence-Garcia, where Miguel Flores has stayed all week.

Miguel Flores agreed to fight Mexico’s Ramirez (24-2-3, 11 KOs, 1 NC) on barely one week’s notice. Ramirez was supposed to face countryman Julio Ceja, but Ceja contracted COVID-19 and was forced to withdraw from their fight.

Flores had been scheduled to box another Mexican southpaw, Isaac Avelar, on the Spence-Garcia undercard.

Ramirez was winning their fight convincingly before that fifth-round knockout.

Flores’ right hand made Ramirez move away from him with a little more than a minute to go in the fourth round, but Ramirez had his way with Flores during the first three rounds.

Ramirez’s right hook cracked Flores with about 55 seconds to in the third round. About 20 seconds later, Ramirez’s straight left backed up Flores.

Ramirez’s left hand and follow-up right uppercut hurt Flores about 40 seconds into the second round. Flores held Ramirez to regain his senses and continued coming forward, but Ramirez landed the harder punches for the remainder of the second round.

Ramirez started strong in the opening round.

His right hook connected with about a minute remaining in the first round. Ramirez landed a straight left to Flores’ body several seconds later and connected with a straight left up top with about 35 seconds to go in that opening round.

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