Poirier picked away at Gaethje with punches from the opening horn, but the latter countered by punishing the lightweight with his feared legkicks. By the middle frames, Poirier was clearly compromised from the kicks to the leg, and his left eye was badly swollen, due to an eyepoke he took. In round three, although Gaethje had a point deducted after he poked Poirier in the eye once again, the fight appeared to be headed in his direction.
In round four, however, Poirier stunned Gaethje with a booming counter left, and after he tagged the latter with several more punches, the fight was stopped.
With the win, Poirier extended his undefeated streak to four, and his overall record to 23-5. Gaethje, meanwhile, has lost two in a row now, and his record fell to 18-2.
Here are the complete results for the event, which went down at the Gila River Arena in Glendale, Arizona.
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Dustin Poirier def. Justin Gaethje via TKO (punches) R4, 0:33
Alex Oliveira def. Carlos Condit via submission (guillotine choke) R2, 3:17
Israel Adesanya def. Marvin Vettori via split decision (29-28, 28-29, 29-28)
Michelle Waterson def. Cortney Casey via split decision (29-28, 28-29, 29-28)
Antonio Carlos Junior def. Tim Boetsch via submission (rear-naked-choke) R1, 4:28
Muslim Salikhov def. Ricky Rainey via KO (punches) R3, 4:12
John Moraga def. Wilson Reis via unanimous decision (29-28, 29-28, 29-28)
Brad Tavares def. Krzysztof Jotko via TKO (punches) R3, 2:16
Gilbert Burns def. Dan Moret via KO (punch) R2, 0:59
Lauren Mueller def. Shana Dobson via unanimous decision (29-28, 29-28, 29-28)
Yushin Okami def. Dhiego Lima via unanimous decision (30-26, 30-26, 30-26)
Adam Wieczorek def. Arjan Bhullar via submission (omoplata) R2, 1:59
Alejandro Perez def. Matthew Lopez via TKO (strikes) R2, 3:42
Luke Sanders def. Patrick Williams via unanimous decision (30-27, 30-27, 29-28)