ATLANTIC CITY – Elin Cederroos ruined Alicia Napoleon-Espinosa’s plan to fight Claressa Shields.

The unknown, undefeated Swede knocked down Napoleon-Espinosa in the second round Friday night, which accounted for the one-point difference on the scorecards of each of the three judges. Mark Consentino, Lawrence Layton and John McKaie all scored their action-packed fight 95-94 for Cederroos, who won their 10-round, 168-pound title unification fight by unanimous decision on the Shields-Ivana Habazin undercard at Ocean Resort Casino’s Ovation Hall.

Cederroos (8-0, 4 KOs) defended her IBF super middleweight title and won the WBA belt from Napoleon-Espinosa (12-2, 7 KOs), of Lindenhurst, New York.

“I’m so happy,” Cederroos told Showtime’s Jim Gray following her upset. “I showd that I can box and take a war. But when I relaxed, the punches just came. It feels so wonderful. Alicia was a great opponent. She’s so professional. We had a fight in the ring and I hope now we are friendly.”

Napoleon-Espinosa was expected to challenge Shields in her next fight. Cederroos wouldn’t commit to facing Shields, a heavy favorite to beat Habazin.

Challenging Shields would require the tall, 34-year-old Cederroos to move down from 168 pounds to 160. A rematch with Napoleon-Espinosa might make more sense based on the competitive, entertaining nature of their fight.

“I didn’t think I lost,” Napoleon-Espinosa said. “I thought that it was fairly close, but I thought I was ahead. It is what it is, but I don’t think that I lost this fight.”

Napoleon-Espinosa and Cederroos traded hard shots for the duration of an entertaining 10th round in which Napoleon-Espinosa bled from a cut over her right eye and Cederroos bled badly from her nose.

Napoleon-Espinosa suffered a significant cut over her right eye in the ninth round.

Cederroos consistently connected on Napoleon-Espinosa during the first half of an action-packed eighth round. Napoleon-Espinosa rallied in the final minute of that round by connecting with numerous right hands.

Napoleon-Espinosa picked apart Cederroos with her right hand throughout a very successful seventh round for her.

Napoleon-Espinosa hit Cederroos with two right hands within the final 15 seconds of the sixth round. Cederroos took those shots better than she had done earlier in the fight.

Napoleon-Espinosa had trouble getting inside on Cederroos throughout the fifth round. Neither fighter landed impactful punches during those two minutes.

Cederroos’ right hand woke up Napoleon-Espinosa in the first minute of the fourth round. She pressed forward and threw several hard shots at Cederroos, none of which appeared to land.

Just before the bell sounded to end the fourth round, though, Napoleon-Espinosa caught Cederroos with a right hand that made her hold.

Napoleon-Espinosa was cautious in the third round because Cederroos dropped her in the second round.

A right hand by Napoleon-Espinosa backed up Cederroos early in the second round, but Cederroos completely changed the course of the fight late in the second round.

A left hook by Cederroos knocked down Napoleon-Espinosa, who fell backward, into the bottom rope. A stunned Napoleon-Espinosa got up and survived until the bell to end the round.

Napoleon-Espinosa nailed Cederroos with a left hook late in the first round that seemed to affect her.

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