LAS VEGAS – Elvis Rodriguez recovered from a slow start Saturday night to knock out a previously unbeaten Olympian in Rodriguez’s return from his first professional defeat.

Mexico’s Juan Pablo Romero seemingly out-boxed Rodriguez during the first three rounds, but Rodriguez dropped him once apiece in the fourth and fifth rounds before their scheduled 10-round welterweight bout was stopped at MGM Grand Garden Arena. Rodriguez nailed Romero with a counter left hand in an exchange that dumped Romero flat on his back late in the fifth round.

Romero reached a sitting position, but he couldn’t get up before referee Robert Hoyle reached the count of 10 with one second to go in the fifth round of the first fight on the pay-per-view portion of the Canelo Alvarez-Caleb Plant undercard.

The Dominican Republic’s Rodriguez (12-1-1, 11 KOs) bounced back from his eight-round, majority-decision defeat to Chicago’s Kenneth Sims Jr. on May 22 at Virgin Hotels Las Vegas.

Promoter Top Rank released Rodriguez from his contract following his loss to Sims (16-2-1, 5 KOs). His victory over Romero marked his debut with Al Haymon’s Premier Boxing Champions.

The 31-year-old Romero, a 2016 Olympian, fell to 14-1 (9 KOs).

Romero recovered from a fourth-round knockdown to make most of the fifth round competitive, until Rodriguez drilled him with the aforementioned  

With just under 1:50 to go in the fourth round, Rodriguez ripped Romero with a right to the body and followed up with a right uppercut. Two lefts and a right by Rodriguez sent Romero to the canvas with about 50 seconds to go in the fourth round.

A stunned Romero beat Hoyle’s count and managed to throw hard shots at Rodriguez by the end of the fourth round.

Romero kept pressuring Rodriguez at the start of the third round and was the busier, more accurate fighter during that round. Rodriguez tried to stand his ground during that round, but

Romero landed a right hand early in the second round during an exchange. He connected with a left-right combination later in the second round that made Rodriguez reset his feet.

Rodriguez and Romero traded hard punches when Rodriguez was backed into a neutral corner late in the first round.

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