Double Olympic gold medalist Claressa Shields became a professional at the end of 2016 and has quickly become one of the sport's biggest poster names.

This weekend, the American had the chance at home in Flint, Michigan to become the boxer in history, men and women, who quickly became the world champion in three different weight classes.

Instead, the match against Ivana Habazin has been canceled with less than 24 hours notice.

"She misses class"

It was during the night's weigh-in that an unidentified person knocked Habazin's coach, James Ali Bashir, unconscious and then fled the arena. Bashir hit his head in the concrete floor and began to bleed profusely.

According to Habazin, the person belongs to Shield's entourage.

- Claressa is big in the mouth and the people around her are always looking for trouble. She and her team lack class, she writes in a long post on Facebook.

Forced to emergency surgery

Television pictures show how Bashir ended up in a hot exchange of words just before the weigh-in. It is unclear if the same person was later behind the attack.

According to ESPN, a bloody Bashir was left lying about 20 minutes before he could be carried to a stretcher and taken to hospital. There he had to undergo reconstructive surgery on his face.

- I sat at the hospital until two in the morning, for a total of twelve hours. I was worried about my coach's health and I think most would have done the same, writes Habazin and continues:

- Claressa says I'm just looking for excuses and that I can bring another coach to the match. Seriously?

James Ali Bashir is a veteran of the boxing world and has worked with former heavyweight king Wladimir Klitschko.

"Feeling insecure here"

The organization WBC, whose world champion belt in super welterweight was at stake, writes that they "strongly distance themselves from the terrible attack that took place in connection with our event".

It is currently unclear if the match will be rescheduled, but WBC further states that they may hand out their own penalties if it turns out that there has been a violation of their regulations.

- We have been threatened and feel insecure here, writes Habazin.

- When my coach has recovered, it's just you and me in the ring, Claressa. Then we'll see how tough you are when you don't have your team with you, she continues.