LAS VEGAS -- After weeks of trash talking from both camps which started thanks to a social media attack from brash Irishman Gary "Spike" O'Sullivan, it was former middleweight titleholder David Lemieux who had the last laugh.

Lemieux (40-4, 34 KOs), long one of the biggest punchers in the 160-pound division, needed just under three minutes to finish O'Sullivan in a first-round knockout that did well to announce the Canadian slugger as a possible future opponent for the winner (or loser) of Saturday's Canelo Alvarez-Gennady Golovkin II main event.

Respect box? Subscribe to my podcast -- In This Corner with Brian Campbell -- where we take an in-depth look at the world of boxing each week.

The 29-year-old Lemieux finally cracked under the weight of O'Sullivan's constant (and profane) verbal assault during fight week when he was criticized for accusing O'Sullivan of assaulting former girlfriends. The drama led all the way into Friday's weigh-in where O'Sullivan called Lemieux "a f---ing asshole" and nearly started a brawl by placing his fist to his face.

Just 2:44 into the opening round come fight night, Lemieux flattened O'Sullivan with a perfect counter left hook to the face that turned his chin violently. Referee Russell Mora initially began to count but waved off the fight seconds later as O'Sullivan (28-3, 20 KOs) struggled to get to his knees.

"Don't piss me off, I guess," Lemieux said. "I didn't like all that trash talk. It was done to me before the fight. I kept it in me until the right time. I'm a respectable fighter and I came in the ring and always respect my opponents and train hard."

Lemieux entered the fight hoping to return to the title picture and put behind him a one-sided decision loss to WBO champion Billy Joe Saunders last December that further exposed Lemieux as a one-trick pony who can punch, but lacks the top-end craft or technique to beat elite opponents.

For complete coverage of Canelo vs. GGG 2, please click here.

"Look, you can't compare me against Billy Joe Saunders to the David Lemieux today," he said. "I'm not the same guy. I was 50 percent against Saudners, who is an expert technician and moves around the ring really good. I am 100 percent healthy and in shape and that's the result."

After the fight, Lemieux said he had no preference as to who would win the main event.

"They are two excellent fighters and I'm looking forward to fighting both of them and the winner of course but there is no middleweight like David Lemieux," he said. "I'm not rooting for anyone. I want to fight both of them but I think it's a 50/50 chance fight. Canelo is an excellent boxer and so is Golovkin."

In 2015, Lemieux lost a middleweight unification bout against Golovkin in another one-sided defeat when he was stopped late after GGG relied almost exclusively on his jab to break Lemieux down. Given his performance on Saturday, Lemieux is hoping for a second chance.

"I once fought Golovkin in his peak so hopefully Golovkin will one day fight Lemieux in his peak and I hope that's what happens," Lemieux said.