Claressa Shields will have to wait for her chance to make more history.

BoxingScene.com has learned that Shields’ scheduled 154-pound title fight against Ivana Habazin was canceled Friday because Habazin’s trainer was viciously assaulted at their weigh-in. Shields and Habazin had not yet weighed in before James Ali Bashir, Habazin’s veteran trainer, was sucker-punched from behind by an unidentified assailant.

Bashir wore a neck brace as he was wheeled out on a stretcher from Dort Federal Credit Union Event Center in Flint, Michigan, site of the weigh-in and Saturday’s card. Flint is the hometown of Shields, a two-time Olympic gold medalist and women’s boxing’s undisputed middleweight champion.

According to TMZ.com, Flint police have a suspect in custody. The suspect’s identity has not been revealed.

A sobbing Habazin, who traveled with Bashir to nearby McLaren Flint Community Medical Center, was visibly upset as she comforted him while awaiting emergency personnel.

She didn’t weigh in before she left the venue, but Shields made weight (153½ pounds). Other fighters scheduled to box Saturday night weighed in as well.

In a video posted by FightHype.com, a bloodied Bashir can be seen lying motionless on the floor. Bashir later confirmed through his Twitter account that he would undergo emergency surgery in Detroit to repair facial fractures sustained during the incident.

Bashir, a New Jersey native, is known for working as an assistant trainer to former heavyweight champion Wladimir Klitschko. He also has worked with former undisputed cruiserweight champ Oleksandr Usyk, and retired heavyweights Monte Barrett, Shannon Briggs, Maurice Harris and Jameel McCline.

Croatia’s Habazin understandably declined to remain in the fight with Shields because her injured trainer wouldn’t have been able to work her corner. Shields, 24, and Habazin, 29, were supposed to box for the vacant WBC and WBO 154-pound championships.

It was not clear as of Friday night if the bout between Shields (9-0, 2 KOs) and Habazin (20-3, 7 KOs) would be rescheduled. Had Shields won Saturday night, she would’ve become the fastest fighter in boxing history, male or female, to win a world title in a third weight class.

That distinction currently belongs to WBA/WBC/WBO lightweight champ Vasiliy Lomachenko, who accomplished that feat in his 12th pro bout.

Friday marked the second time the Shields-Habazin bout didn’t proceed as planned. They were supposed to fight August 17, but it was postponed until Saturday night because Shields suffered a knee injury during training.

Showtime was supposed to televise Shields-Habazin as the main event of a tripleheader. The two fights that were to precede Shields-Habazin still will be broadcast, beginning at 9 p.m. ET/6 p.m. PT.

Those 10-rounders will feature undefeated welterweight prospect Jaron Ennis and unbeaten heavyweight prospect Jermaine Franklin.

Philadelphia’s Ennis (23-0, 21 KOs) is scheduled to square off against Argentina’s Demian Daniel Fernandez (12-1, 5 KOs) in what’s now the main event. Franklin (19-0, 13 KOs), of Saginaw, Michigan, will face the Czech Republic’s Pavel Sour (11-1, 6 KOs). 

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