The fight against Poirier in three-months time will be Diaz's first in the lightweight division in almost three years and he will now take on one of the top-ranked contenders in the weight class.
He balked at participating in Saturday's UFC 227 at Staples Center against former two-division champion Georges St-Pierre, with a representative saying Diaz felt that St-Pierre was his brother's rival, and then St-Pierre fell ill. And on top of the fact that he's now on a four-win winning streak, but is also considered one of the top lightweight contenders in the UFC, with being ranked at third on the official UFC rankings.More news: Trump Defends Son's Meeting With Russians as `Totally Legal'
Poirier (24-5) has surged to No. 3 in the UFC lightweight rankings by winning eight of his last ten UFC Octagon appearances.
There has been no announcement for the main event at UFC 230 but there are several scheduled fights rumored for the card.
Poirier, meanwhile, is fresh off of a TKO victory over Eddie Alvarez on July 28. The last time the pair met, Rockhold defeated New York's Weidman by fourth-round technical knockout to capture the middleweight belt at Las Vegas in December 2015.
The match-up will officially be announced at a press conference in Los Angeles this evening, with rumours suggesting that McGregor's eagerly anticipated fight against Khabib Nurmagomedov will also be confirmed.