Undisputed middleweight boxing champion Claressa Shields' brother has pleaded guilty to assault and could face up to a year in prison.

Artis Mack, 28, was a member of Shields' entourage last October during her fight with Ivana Habazin when he had an altercation with the Croatian's trainer James Ali Bashir at the weigh-in of their fight in Flint, Michigan.

Bashir, 68, was taken to hospital where his injuries were treated, while the fight, which was scheduled for the following day, was cancelled.

And Mack's representative at the hearing on Monday, Frank Manley, said he considers the guilty plea a victory given the circumstances.

As first reported by World Boxing News, Manley told mlive.com: “It was bad for the city, bad for his sister and certainly bad for everybody involved.

“We consider it a victory. Mr Mack was confronted with fighting words and very emotional and provocative language. He was concerned about the safety of his sister.

“I think there were words in there that were racially tinged, and in his mind those were fighting words and so forth allowed him to go forward and protect his sister. We felt that it was in his best interest to resolve this matter at this time."

Mack will be sentenced on March 10 and could face up to a year in jail as well as a $1,000 fine.

In the ring, Shields' bout with Habazin was re-arranged for January and the two-time Olympic gold medallist secured a unanimous decision victory.

In doing so, the American also made history by becoming a three-weight world champion in the fewest number of professional fights by any man or woman.