Jorge Masvidal beat Nate Diaz to capture the UFC's newly minted "BMF" title after the cageside doctor stopped the fight before the start of the fourth round due to a horrific cut to Diaz's eye.
The belt for the main event at Madison Square Garden was carried to ringside by former WWE-superstar-turned-actor Dwayne "The Rock" Johnson in a highly anticipated fight between two of the organisation's most notorious fighters.
Sitting at ringside was US President Donald Trump, who was largely booed by the New York crowd, and boxing legend Roberto Duran.
When the bell rang the fight didn't disappoint, with both Masvidal and Diaz going toe-to-toe in the opening exchanges and Diaz suffering the cut above his right eye from a Masvidal punch in the first round.
Masvidal was ahead on all three judges' scorecards when the cageside doctor inspected Diaz's eye after Round 3. Though the California native insisted he was good to continue, the doctor would not be swayed and informed referee Dan Miragliotta to call off the bout.
Miami-based Masvidal, who extended his Mixed Martial Arts record to 35 wins against 13 losses, said in his post-match interview he would grant Diaz a rematch.
"I swear, we're running it back," while Diaz admitted he was shocked the doctor stopped the fight, saying: "I didn’t think they were going to stop it. I was just getting ready to get started."
The defeat for Diaz was the 12th of his MMA career against 20 wins and could scupper a potentially lucrative third bout against Irishman Conor McGregor.
Diaz won the pair's first fight in March 2016 before losing a majority decision in the rematch five months later.
It was the second sporting event Mr Trump had attended in a week and came a day after he said he was changing his residence from his home state of New York to Florida.
The president was seen clapping and at one point stood up for a better view as 20,000 pumped-up fans screamed and swore amid an electric atmosphere at the pay-per-view spectacle.
Jeers rang out as Mr Trump pumped his fist and waved at the crowd as he walked into the arena as well as posed for pictures alongside former welterweight king Duran.
There was no repeat of the loud chants of "lock him up" that greeted Trump when he attended a World Series baseball game last weekend, but loud jeers rung out whenever his image appeared on the big screens at the Garden.
Earlier, UFC lightweight contender Kevin Lee scored the best win of his career with a contender for knockout of the year as he beat previously undefeated Gregor Gillespie.
Despite a fairly even start, Lee made the breakthrough when he connected with a right hand and then a huge kick to the Gillespie's chin that left him unconscious 13 seconds before the end of the opening round.
"It feels great to get back into the win column," said Lee, who had lost his two previous bouts to Rafael dos Anjos and Al Iaquinta.