Claressa Shields sealed a dominant points win over Christina Hammer to become the undisputed women’s middleweight champion in Atlantic City.

The unbeaten American already held the WBC, IBF and WBA belts, adding the last remaining WBO title as she claimed a wide unanimous decision with three scores of 98-82 from the judges at the Boardwalk Hall.

Shields had made an aggressive start to the fight, easily negating the longer reach of Hammer to deliver big right hands from the opening bell, and troubled the German with a combination in the second round.

Hammer was forced into reverse, offering little in response, and had to withstand another big right hand in the fourth, while Shields was swaying away from her opponent’s occasional punches and pumped her jab in the sixth.

With the fight slipping away, Hammer stood and traded in the seventh, and was hurt by an overhand right from Shields, who continued to pile on punches in the eighth, with the bell denying her a stoppage.

Hammer wisely opted to remain on her back foot for the ninth, staying away from further danger, but would connect with a crisp left hand in the last, although Shields could celebrate a historic victory as the bell sounded.

On the undercard, unbeaten heavyweight prospect Jermaine Franklin Jr claimed a unanimous decision win over Rydell Booker with scores of 99-91, 98-92 and 98-92 to bring up his 18th victory.

But fellow heavyweight Otto Wallin’s US debut ended in a no decision following a clash of heads with Nick Kisner in the first round.

(c) Sky News 2019: Claressa Shields defeats Christina Hammer to become undisputed middleweight champion