LAS VEGAS - Kenneth Sims’ debut under the Golden Boy Promotions’ banner was a successful one.

Sims won by fifth-round technical knockout over late-sub Jonathan Romero. The one-way fight ended when Romero complained of blurred vision after the fifth round of their DAZN aired bout Saturday at Mandalay Bay's Michelob ULTRA Arena.

Romero took the fight on 24 hours’ notice after original opponent Jair Valtierra dropped out of the fight.

From the opening bell, Sims backed Romero in a corner or against the ropes, unleashing vicious punches to the body. Romero was game, willing to fight back, but would leave himself open to getting countered with a hook or cross to the head.

By round four, Sims focused his attack to the head, connecting with uppercuts to Romero’s head. To his credit, Romero fought back, throwing and landing sweeping left hooks or right crosses to the head of Sims.

During the following round, Sims focused his attack to the body, landing lead left hands and right crosses to the body. Midway through the round, a right cross momentarily staggered Romero. Despite fighting with his back against the corner, Romero was able to gather himself and fight back, keeping Sims at bay.

After the end of round five, Romero’s corner told referee Robert Hoyle to stop the fight. Romero hung in there as long as he could, but had taken a lot of punches flush to the head, prompting his corner to look out for his health.

Sims improved to 21-2-1, 8 knockouts. The 30-year-old Chicago native had not fought since May 13 of last year, defeating Botirzhon Akhmedov by majority decision. Sims has now won his last eight fights since a decision loss to Samuel Teah in November 2018, including wins over Elvis Rodriguez and Keeshawn Williams, both of whom were unbeaten when they faced Sims.

“I felt like I was making my professional debut again,” said Sims after the fight. “It was great to be in the ring again after so long - sparring is sparring, and to be inside a real fight was something I was really happy about. I felt great in being able to get my groove back and catch my distance with my gloves laced up again.

“I am paying attention to the (140-pound) division, and there are some incredible fights for me at junior welterweight - Jose Ramirez, Arnold Barboza, etc. I’ll be watching.”

Romero, who is originally from Cali, Colombia and now resides in the Las Vegas suburb of Henderson, falls to 35-5, 19 KOs. In his previous fight on July 13 in Modesto, California, Romero lost a one-sided decision to once-beaten Manuel Jaimes.

The 37-year-old has now lost his last four fights, including knockout wins to unbeaten junior lightweight contender Albert Bell and former world title challenger Abraham Nova.