Promoter Ben Shalom of BOXXER has revealed that middleweight champions Claressa Shields and Savannah Marshall have both signed for an undisputed showdown in early September.

The fight was initially planned to take place in July, but it was pushed back when Marshall sustained an arm injury and underwent a minor surgical procedure.

Shields, who believes Marshall exaggerated her injury to buy more time to prepare, threatened to walk away if the contest was pushed back any further than September.

"Early September - both fighters are ready, both fighters are signed," Shalom told Sky Sports News.

"I can't wait. It's taken a while. Claressa has finally got her match. It's the first time we're seeing a genuine rivalry in women's boxing, and that's a sign of the times."

The venue is still being worked out, with London and Newcastle as the two frontrunners to host.

"We are very close to finalizing the venue," Shalom added.

"The fight's got so big now that it needs an international venue. It will happen in the UK - all the venues want it. It's going to be between Newcastle and London, we'll see."

Both undefeated champions have been in action this year.

Marshall retained her WBO title when she brutally knocked out Femke Hermans in April, while Shields secured a one-sided decision win over Ema Kozin to retain the WBA, WBC, IBF world titles in February.

Shields, a two-time Olympic gold medal winner, is looking to avenge the only defeat of her boxing run, which took place in the amateurs, when she was 17 and lost a decision to Marshall in 2012.