ATLANTA – Lionell Thompson made the most of what only could’ve been viewed as his last chance to prove himself Saturday night.

The career-long light heavyweight knocked down Jose Uzcategui in the first round of Thompson’s super-middleweight debut and out-boxed the former 168-pound champion to win a unanimous decision. All three judges – Max DeLuca (95-94), Harold Hunt (96-92) and Nola Oliver (96-92) – scored their 12-round fight for Thompson in the first of three bouts Showtime televised from State Farm Arena.

Uzcategui (29-4, 24 KOs) was a 10-1 favorite to beat the 34-year-old Thompson, who’s promoted by Floyd Mayweather’s company. But it was Thompson (22-5, 12 KOs) who recorded the most noteworthy win of his 10-year pro career on the Gervonta Davis-Yuriorkis Gamboa undercard.

Thompson, a Las Vegas resident raised in Buffalo, New York, fought at the super middleweight limit of 168 pounds for the first time since he turned pro in February 2009. Each of his previous 26 professional fights were contested either at light heavyweight or cruiserweight.

“Moving down to 168 [pounds], I was a little worried for my first fight, but I felt great,” Thompson said. “I still had the power at this weight, and I hurt him a few times. This is my weight class now, and I think I have a real chance at becoming super middleweight champion and putting my city on the map as the first world champion from Buffalo.”

Uzcategui, 29, lost for the second time in his past three fights.

Caleb Plant won the IBF super middleweight title from Uzcategui by winning a 12-round unanimous decision January 13 at Microsoft Theater in Los Angeles. The native Venezuelan knocked out a lesser opponent than Thompson, Roberto Valdez (10-10-1, 7 KOs), in the first round of his first fight following his loss to Plant on September 21 in Tijuana, Mexico, where Uzcategui now resides.

“I thought the decision was fair,” Uzcategui said. “I don’t want to make any excuses. He came to fight.”

Uzcategui added, though, that having only one round of action on his record since Plant beat him hurt his cause Saturday night.

“The distance from my last fight definitely showed,” Uzcategui said. “I was very rusty. I need to get back in the gym, train harder and hopefully get another fight in the next few months.”

Uzcategui fought out of a southpaw stance in the 10th round. Thompson out-landed Uzcategui in that round, however, as Uzcategui mostly missed while ineffectively pressuring him.

Thompson jabbed Uzcategui to the body and landed a couple right hands as he stuck and moved during the ninth round. Uzcategui pressured throughout the eighth round, but he couldn’t land anything that hurt Thompson.

Thompson’s right uppercut turned Uzcategui’s head sideways in the seventh round, but Uzcategui didn’t appear to be hurt.

Thompson began squinting late in the seventh round. By then, Thompson had a cut over his right eye and some swelling above his left eye.

Thompson drilled Uzcategui with a straight right near the end of the sixth round. 

A left hook and overhand right by Uzcategui made Thompson retreat late in the fifth round. Thompson shook his head to show Uzcategui that he wasn’t hurt, despite eating those punches.

Referee George Chip deducted a point from Thompson for holding early in the fourth round. He had told Thompson in the third round that he had issued his last warning for holding.

Thompson’s mouthpiece came out during an exchange toward the end of the fourth round. Chip separated the fighters, picked it up, called for time, had Uzcategui’s trainer rinse it off and then went to put it in Uzcategui’s mouth, before realizing it was Thompson’s mouthpiece.

A left hook by Uzcategui early in the third round caused Thompson to hold him early in the third round. Chip warned Thompson for holding twice later in the third

Uzcategui hit Thompson with a flush left hook early in the second round. Thompson mostly kept his distance from the aggressive Uzcategui for the rest of the second round.

A hard jab by Uzcategui snapped back Thompson’s head just after the halfway point of the first round. Uzcategui was in control of the opening round before Thompson tattooed him with a perfect, straight right hand that sent Uzcategui to the seat of his trunks with under 10 seconds remaining in it.

A smiling Uzcategui easily beat the count and the bell sounded soon thereafter.

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