LOS ANGELES (AFP) -- Conor McGregor made a triumphant return to the UFC octagon on Saturday, pummelling Donald "Cowboy" Cerrone for a technical knockout victory in just 40 seconds.

The mixed martial arts superstar from Ireland -- returning to the Ultimate Fighting Championship for the first time since he was battered into submission by arch-rival Khabib Nurmagomedov in October 2018 -- overpowered his American foe without ever being tested.

After charging in with a left and missing, McGregor immediately bloodied a clinching Cerrone's nose with an upward shoulder strike -- quickly followed by another.

As soon as Cerrone stepped back, McGregor caught him on the jaw with a high kick, then buried him under a hail of punches.

Referee Herb Dean stepped in to call a halt to the welterweight bout 40 seconds into the first round at the T-Mobile Arena in Las Vegas.

"I made history here tonight," McGregor said. "I'm the first UFC fighter to secure knockouts in featherweight, lightweight and now welterweight.

"Etch my name in the history books one more time," he said. "For the Irish people. For my mom back home."

McGregor who took his record to 22-4, was the first UFC fighter to hold two championship belts at the same time.

He achieved that feat in 2016, when he stopped Eddie Alvarez in a lightweight title fight, adding that belt to his featherweight title.

But he hadn't won since.

That triumph was followed by a loss to boxing great Floyd Mayweather in a cross-combat superfight in 2017, his loss to Nurmagomedov, announcements of retirements and returns to fighting.

Along the way there were brushes with authorities outside the octagon. He pleaded guilty to hitting a man in a bar in Ireland and was accused of smashing a fan's phone in Florida.

The New York Times reported he is the subject of two alleged sexual assault investigations in Ireland.

Nevertheless, McGregor remains the most popular fighter in UFC history, and his return brought out stars including British heavyweight Tyson Fury and New England Patriots superstar quarterback Tom Brady for the sold-out show.

And McGregor didn't disappoint against Cerrone, an experienced veteran whose 36 wins included the most knockouts (20) in UFC.

"He destroyed me," Cerrone, said, "100 percent I've never seen anything like it. I got my ass whipped early."

Although there was no title at stake, McGregor said the outcome was a harbinger of things to come.

"I like this (welterweight) division," he said. "I feel really good. I came out of here unscathed. I've got work to do to get back to where I was."

McGregor has expressed interest in a rematch with Nurmagomedov, who is scheduled to defend his lightweight title in April against Tony Ferguson.

At welterweight there is the enticing prospect of Jorge Masvidal.

UFC boss Dana White said he was "blown away" by McGregor's performance.

"He looked fast, he hit hard, he had a game plan and he finished a real tough kid who came to win," White said, adding that in his opinion the obvious fight to point McGregor toward was a rematch with the 28-0 Nurmagomedov.

"Khabib is the fight to make," White said. "We're looking at Hagler-Hearns. We're looking at, like, Ali-Foreman, Ali-Frazier. This is a massive fight with global appeal."

White was unruffled by the chance that his top draw McGregor could be lured back to the boxing ring, for a Mayweather rematch or even a clash with Filipino fight king Manny Pacquiao.

"These are great problems to have," White said. (AFP)