IBF, WBC, WBA middleweight champion Claressa “G.W.O.A.T.” Shields believes her 2012 amateur defeat at the hands of WBO champion, Savannah Marshall, was fluke.

They will settle the score in the pros, on Saturday, September 10 from The O2 in London.

The amateur loss to Marshall is the sole defeat of Shields' boxing career.

Their undefeated records, and the undisputed middleweight crown, will be at stake when they collide next month.

There are some oddsmakers who are listing Marshall as the favorite - due to her punching power. Marshall has knocked out 10 of her 12 opponents.

“To all of you that are doubting me, just make sure you apologize after the fight. Say, ‘We were wrong.’ You don’t have to say you’re the G.W.O.A.T. Just say, ‘We were wrong, you’re the best and we respect you.’ And that you respect my hard work and my accomplishments because (Marshall) was the fluke," Shields said.

"Her beating me in 2012 before the Olympics was the fluke of her career. That was her biggest achievement. After that, downhill. It wasn’t a fluke that I won the 2012 Olympics because I won it again, and I won the world championships three times after that. So, she was the fluke, and she’s still a fluke because she’s knocked out a whole bunch of bums.”

Shields believes the power of Marshall is being overrated by a lot of observers and fans.

“So, they want me to lose and they’re going to say anything to make her feel like she’s better. I mean look, I accept her knockouts because they’re there. She’s 12-0 with 10 knockouts, but go and look at those girls’ records and then tell me whether she should be knocking them out, or not. And you’re going to say, ‘Yea, you should be knocking out somebody that’s 4-25. You should be knocking out somebody that’s 11-75.’ Plus, you’re fighting them on three days’ notice, a week’s notice. You’re supposed to knock girls out like that," Shields said.