Lorenzo Simpson got off to a strong start Friday night, withstood a debatable knockdown late in the fifth round and remained undefeated by out-pointing previously undefeated Sonny Duversonne.

The junior middleweight prospect’s punch output decreased in the second half of their eight-round bout, but he fended off an aggressive Duversonne in the final four rounds to win on all three scorecards at MGM Grand Conference Center in Las Vegas. Baltimore’s Simpson was active enough in the middle rounds to maintain his lead and became aggressive again during the final round.

Two judges, Tim Cheatham and Max De Luca, scored their fight 78-73 for Simpson. Judge Chris Migliore scored the action 79-73 for Simpson, who improved to 9-0 (5 KOs).

Miami’s Duversonne lost for the first time as a pro (11-1-2, 8 KOs).

Simpson drilled Duversonne with a straight left hand with about 30 seconds to go in their fight. Earlier in the eight, Simpson landed a straight left to Duversonne’s body and came back quickly with a right downstairs.

Simpson shook off a questionable knockdown late in the fifth round to out-box Duversonne while boxing off his back foot in the sixth and seventh rounds.

Just before the end of the fifth round, referee Mike Ortega scored a knockdown for Duversonne, who landed a right hand that knocked Simpson off balance and made him use his right glove to hold himself upright. Simpson protested because he thought their feet got tangled, but it counted as the first knockdown of his career.

Duversonne was aggressive in the fourth round, but Simpson eluded most of his punches. Simpson wasn’t as effective offensively in that round as he had been in the first three rounds.

A straight left by Simpson backed up Simpson about 30 seconds into the third round. Simpson unloaded a barrage of punches to Duversonne’s body several seconds later.

A right hand by Duversonne landed as Simpson moved backward just before the third round ended.

A straight left by Simpson landed with just under 50 seconds to go in the second round. Simpson connected with a left-right combination just before the midway point of the second round.

Simpson landed a left to Duversonne’s body with just over a minute to go in the first round. Duversonne landed a straight right hand toward the end of the opening round.

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