WBO middleweight champion Savannah Marshall is oozing in confidence as the moment gets closer for the scheduled showdown with IBF, WBC, WBA champion Claressa Shields.

The undisputed fight takes place at the O2 Arena in London on September 10.

Marshall holds an amateur decision win over Shields. That was the only boxing blemish on her record as a pro and amateur.

The back-and-forth war of words has made Marshall become obsessive with the mindset of beating Shields.

"Non-stop [thinking about beating her]," Marshall said to Sky Sports. "I'm constantly thinking about this fight. I can't think of anything else. This is a chance for me to change my life. Come September 10 my life will never be the same again and I only get one shot. So this is why I'm training the way I am. This is why I'm preparing the way I am. And that's all I need, just one shot.

"I cannot wait. I've been waiting for this since I turned pro," she added. "I've waited for this for five or six years and now it's here. Now it's coming and the weeks are just flying and I wouldn't have it any other way."

Marshall shot down some of the statements from Shields, who believes the British boxer was looking to avoid their collision.

"I've given up trying to crack that girl, she contradicts herself so much. What says I don't want this fight when the date's set, I'm in training camp? What about that says I don't want this fight?" Marshall responded. "She's a big question mark, let's just leave it at that.

"She can't handle defeat. I beat her 10 years ago [as amateurs]. She says it doesn't bother her but when someone is asking, she's going, 'She never beat me!' So I'm thinking, your body language, your tone of voice is saying different. No, she's not going to take this loss well. She didn't take the first one well, she's not going to take the second one well."