Alex Pereira has caused a boilover at Ultimate Fighting Championship (UFC) 320 with a first-round technical knockout (TKO) of heavily favoured Magomed Ankalaev in Las Vegas, regaining his undisputed light heavyweight championship belt and avenging his defeat by the Russian seven months earlier.

Pereira took only one minute and 20 seconds to defeat Ankalaev after he dropped the 33-year-old champion with a huge right hook less than a minute into the contest on Saturday at T-Mobile Arena.

The Brazilian then finished off the fight with a flurry of punches and elbows before the match referee called off the bout.

Ankalaev, who had never been knocked out in a UFC match, had his 14-match unbeaten run ended, going back to his promotional debut at a UFC Fight Night in March 2018.

Pre-fight, Pereira was the decided underdog, with Ankalaev backed by 89 percent of the fight bets at BetMGM.

Ankalaev (20-2-1, 12-2-1 UFC) had already beaten Pereira (13-3, 10-2 UFC) in their first bout at UFC 313 on March 8. Pereira claimed he fought at just 40 percent of his usual capabilities due to injury.

Pereira’s victory makes him a two-time UFC light heavyweight champion.

The 38-year-old’s victory revives the light heavyweight title picture, taking the belt from a fighter in Ankalaev who did little to inspire hope for the future of the division. With Jiri Prochazka also winning his bout by stunning knockout, it awakened the potential for a third bout against Pereira for the belt.

Pereira, right, punches Magomed Ankalaev in the first round moments before the fight was stopped by the match referee due to technical knockout [Sean M Haffey/Getty Images via AFP]
In the earlier co-main event championship bout, Merab Dvalishvili (21-4-0) defended his undisputed bantamweight crown with a unanimous decision against Cory Sandhagen (18-6-0) in their five-round contest.

The three judges scored it for Dvalishvili: 49-45, 49-45 and 49-46.

The most anticipated action of the main card began with a light heavyweight war between Prochazka (32-5-1) and Khalil Rountree Jr (15-7-0). With a loss likely in the balance late in the third, the Czech fighter landed a devastating combination that knocked Rountree out cold with two minutes left on the clock.

Rountree gained an early advantage by landing multiple series of high-calibre combinations in the first round that left Prochazka clearly stumbling into the second. The exchanges also tired Rountree, allowing Prochazka a chance to find a window with his third-round explosion.

Jiri Prochazka, left, of the Czech Republic fights Khalil Rountree Jr. of the United States during a light heavyweight bout in UFC 320 [ Sean M. Haffey/Getty Images via AFP]