IBF, WBO super featherweight champion Mikaela Mayer is backing Claressa Shields to topple Savannah Marshall in a planned middleweight unification.

The two champions traded harsh words, face to face, last Saturday in Newcastle, in the aftermath of Marshall's most recent defense.

Mayer believes Shields' speed and output will prove to be too much for the power punching Marshall to handle.

"I'm going to sound biased, because Claressa is my teammate and friend, but although Savannah is proven to have power, I think that Claressa's punch count and speed is a lot for anyone at that weight to handle," Mayer said to Sky Sports.

"I do see her coming out on top, but either way I'll be there to support. I can't wait for it. Just her ferociousness, when she gets in the ring. She doesn't like to lose and so she has a chip on her shoulder because Savannah is the only one to ever beat her. I think we're going to see a different Claressa Shields that night, a scarier one!"

Marshall is the only boxer to ever beat Shields in a boxing ring. Shields, who eventually won two Olympic gold medals, was a young boxer when she lost an amateur bout to Marshall. 

"Savannah is a great boxer. I know here from the amateurs. She has obviously crossed over into the pros very well, she has a good name over there - people love her - and she seems to have a good pro style, some good pop. I think that her fight with Claressa Shields is going to be a great fight," Mayer said.

"This is what women's boxing needs, we need these rivalries, these big fights to happen. We've had so many in the past couple of years and this is just another of those really great ones. I can't wait to see it."