The fight was originally scheduled for the main event in Ireland, but Duffy suffered a flash knockout on his final day of sparring just before leaving his camp in Montreal.
When he arrived in Ireland and word of the knockout got out to UFC officials, they told Duffy to undergo a medical exam. Doctors determined he had a mild concussion as a result of the blow to the head, and he was deemed medically ineligible to compete.
So the fight was canceled and both fighters were pulled from the card.
Now the UFC has opted to reschedule the fight for early 2016 with Poirier meeting Duffy in a featured bout on the New Year’s card in Las Vegas.
The lightweight bout joins an already stacked show including the main event that pits Poirier’s teammate Robbie Lawler against Carlos Condit in a headline fight with the welterweight title up for grabs.