In the co-main event, Derrick Lewis weathered a storm to earn a third-round knockout victory over Marcin Tybura. Medeiros went to the body, Cerrone shot in, was fought off but launched a knee in the clinch.
But near the end of a busy first round, Cerrone stung Medeiros with a straight right that took the string out of his legs, then pounced on him for a TKO finish just two seconds before the end of the round.
Spinning kick from Medeiros lands to the body. In the worst slump of his career, Cowboy Cerrone was on a three-fight skid, and had flirted with heading back to lightweight. Medeiros wasn't able to continue his forward pressure once Cerrone got in his rhythm.
After both fighters traded big punches in the closing seconds of Round 1, Cerrone caught Medeiros with a looping left hook behind the head and a flawless right cross on the chin to floor him. Cerrone knocked down Medeiros and the two embraced.
Cerrone first wobbled Medeiros at the 2:41 mark of the round, but let Medeiros back to his feet after Yancy slipped on the canvas. Right-hand lands by Medeiros, countered by Cerrone with an uppercut. Cerrone with Medeiros against the cage but he flips to dominant position.
They break free and Cerrone lands a right hand. Cerrone threw a couple of haymakers on the ground but Medeiros was unable to defend himself and referee Herb Dean stopped the fight at 4 minutes, 58 seconds.