WBA world bantamweight champion Jamie McDonnell is set to face WBA Super belt-holder Rau'shee Warren.
Doncaster's McDonnell (28-2-1-KO13) has held the regular title for more than two years and made his latest defence in April - halting Fernando Vargas in the ninth round at The O2.
Warren (14-1-KO4), a 2012 Olympic champion who hails from Cincinnati, won a rematch with Juan Carlos Payano in Chicago on June 18 to seize the WBA Super crown, and the governing body have now ordered their two champions to agree terms to fight within the next 30 days.
McDonnell's trainer, Dave Coldwell, said in an interview reported on World Boxing News: "It was a solid win for Warren but one that doesn't really worry myself or Jamie.
"He made a good start and built himself a good lead and it was obvious he learnt the lessons from the first fight which shows he can adapt.
"Payano is someone we've looked at for Jamie before and is a good fighter but I still think that Jamie is the man in the division and that his size and fitness plus his underrated boxing ability which is getting better and better would be enough against Warren.
"People forget that I've only been with Jamie for five minutes and he's still learning stuff every single training session with me. We're already at the top end of the division and he's only going to get better."
Other world bantamweight champions include WBC king Shinsuke Yamanaka (25-0-2-KO17), WBO holder Pungluang Sor Singyu (52-3-KO35) and IBF champion Lee Haskins (33-3-KO14).