The 32-year-old - who stopped Conor McGregor in Las Vegas in June - shared a cryptic post referencing a lyric from Stevie Wonder's number one hit to his 750k followers on Monday which read: "Signed, Sealed, Delivered."
And several sources close to the American's camp confirmed to GIVEMESPORT that The Diamond was indeed referring to an upcoming clash against 'Do Bronx'.
UFC president Dana White has been working on sorting out a high-stakes shootout between lightweight king Oliveira, 31, and former interim strap-holder Poirier for several months now, much to the annoyance of Justin Gaethje, who has openly accused the Brazilian of being 'a quitter'.
But Poirier respectfully disagrees, as he feels that Oliveira 'showed championship mentality' in his most recent fight against Michael Chandler for the vacant lightweight title at UFC 262 on May 15.
Poirier, 32, told MMA Fighting: "I've seen Charles in a lot of fights.
"He's been in a lot of fights at a high level. So, I've seen him kind of fold in fights before. But I've also seen him rise to the occasion and show up in adversity.
"If he was a quitter, he had a chance to quit when [Michael] Chandler hurt him. But he came back and put him away... The guy showed championship mentality.
"Got hurt, pulled it together, finish the guy, I mean, there was no quit that night."
Gaethje is up next against fellow American Chandler on November 6 at Madison Square Garden in New York City as he looks to kickstart his comeback.
Poirier will follow suit little more than a month later when he takes on Oliveira in the main event of UFC 269 on December 11.
Can you get full marks on this ultimate Conor McGregor quiz?