ATLANTIC CITY – Jacob Bonas initially looked like he would have a tough time Friday night with Christian Rivera.

Rivera rocked Bonas with a right hand in the first round, but Bonas withstood that trouble, regained control of their four-round fight and remained unbeaten on the Claressa Shields-Ivana Habazin undercard at Ocean Resort Casino’s Ovation Hall. Bonas battered Rivera with several right hands and left hooks apiece during a one-sided second round and won each of the final three rounds on the scorecards of all three judges.

The 26-year-old Bonas, a welterweight prospect from Detroit, improved to 6-0-1. The 27-year-old Rivera, of Highwood, Illinois, dropped to 1-1-1.

In the card’s first fight Friday night, Joseph Bonas, Jacob’s twin brother, scored a second-round technical knockout of Glenn Mitchell in a junior middleweight match scheduled for four rounds.

Bonas drilled Mitchell with a left hook that wobbled him when Mitchell’s back was against the ropes. Another hard left hook by Bonas caused referee Ricky Gonzalez to step in and stop the fight while Mitchell was still standing.

The time of the stoppage was 1:55 of the second round. 

In the final fight before Showtime’s telecast started, Russian heavyweight prospect Apti Davtaev knocked out Keith Barr in the third round of a bout scheduled for six rounds.

The 6-feet-5 Davtaev knocked down Barr with a right hand in the second round. He also hit Barr when he was down, but Gonzalez didn’t penalize him.

Barr made it to the third round, but Davtaev drilled him with another right hand that left Barr beneath a bottom rope. Barr got up again, but he stumbled and Gonzalez stopped the fight 38 seconds into the third round.

Davtaev upped his record to 19-0-1 and produced his 18th knockout. Barr (20-13-1, 8 KOs), a southpaw from Glenville, West Virginia, lost by knockout for the ninth time since he turned pro 10 years ago.

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