From what we're aware the bout between Diaz and Ao has not yet had a date or venue set though will see the men currently ranked #1, Diaz, and #2, Ao, battle against each other. The winner will be set to fight Flanagan for the vacant title.
For those who are unaware Ao is known to be actively chasing a Lightweight title as he attempts to become just the second Japanese fighter to become a 3-weight world champion, he is also known to want to replicate the feat of close friend and Teiken stablemate Jorge Linares, who won titles at 126, 130 and 135lbs.
As for Diaz he'll be hoping to become a world champion for the second time and the first time since March 2008 when he lost his unified, WBA/WBO/IBF, Lightweight titles to Nate Campbell.
We're awaiting further details on this bout though hope to hear it officially announced in the coming days.
(Image courtesy of Teiken)