Alex Pereira celebrates his victory.
CNN  — 

Alex Pereira became the undisputed middleweight UFC champion on Saturday, defeating Israel Adesanya on a technical knock-out in front of a sold-out Madison Square Gardens in New York.

It was a stunning come-from-behind victory with Pereira, competing in just his fourth UFC fight and eighth overall MMA fight, billed as the underdog against Adesanya who was attempting to win a record sixth consecutive title defense.

And for much of the fight, it seemed as though Adesanya would achieve that record with Pereira languishing behind on the judges’ scorecards until the final round.

But the Brazilian rallied and hit Adesanya with a flurry of shots in the fifth round to force a referee stoppage and a TKO victory.

“I’m very happy,” Pereira said afterwards, according the UFC website. “It was an excellent work. And I’m not just saying from when I entered the Organization but everything I’ve been doing to get here.

“And what I did to be here getting the belt. It was very difficult. I had to overcome some tough opponents but I did it.”

Alex Pereira battles Israel Adesanya.

The two men had met twice previously in kickboxing before they joined the UFC. Pereira had won both bouts, becoming the only man to ever knock out Adesanya.

Adesanya landed the first decisive blow of the night with a one-two that had Pereira reeling but it came in the final seconds of the first round, allowing the 35-year-old to recover for the next round.

And the defending champion’s onslaught continued in the next three rounds, leaving Adesanya ahead on all three judges’ scorecards going into the fifth and final round.

Aware that he needed to find the finish in the fifth round, Pereira unleashed all his power and Adesanya ultimately couldn’t offer a response.

Meanwhile, in the co-main event, Zhang Weili won the women’s strawweight Championship, the second title of her career, by defeating Carla Esparaza by submission with a rear-naked choke in the second round.

“Today is like a dream come true. Ever since I lost the belt, I’ve dreamt of this moment,” she said afterwards, according to the BBC.