CNN  —  Claressa Shields oozed confidence ahead of her heavyweight world title fight on Sunday, shutting down any possibility that her opponent Danielle Perkins could win. The American, who nicknames herself the GWOAT or “Greatest Woman of All Time,” is seeking to become the undisputed world champion in three different weight classes, an extraordinary achievement. “If Danielle don’t keep her hands up, she’s gonna get put on her back pockets,” Shields told CNN’s Patrick Snell before the fight.