Boxing world champion Patrick Teixeira hits UFC superstar Conor McGregor with staggering trash talk

World champion boxer Patrick Teixeira has unleashed an extraordinary barrage of words at UFC superstar Conor McGregor, branding the Irishman "a real clown" and declaring he'd "ruin his career" if they fought.

Teixeira will aim to defend his WBO super welterweight title when he takes on Argentina's Brian Castano in California on February 13.

But the Brazilian is clearly looking beyond his clash with Castano and burning to meet McGregor in the ring, who's pulled on the boxing gloves just once in his professional combat career.

McGregor is set to square off with American Dustin Poirier in UFC 257 on Fight Island in Abu Dhabi on Sunday, six years after they first clashed.

And going by Teixeira's enormous spray, he thinks McGregor should stick to the UFC and forget about his boxing aspirations.

"He's thinking because Floyd (Mayweather) gave him a few rounds to work with, he's a boxer," Teixeira told The Sun.

"I honestly wouldn't do the same thing as Floyd; I would exterminate him in two rounds, one for him to go up and the other to go down. He would take a beating.

"Conor is just delusional, a real clown. Now, I want to beat that clown up and retire him from the sport of boxing and UFC."

McGregor made his professional boxing debut against legendary American Floyd Mayweather in 2017, in which he reached the 10th round but was defeated by a technical knockout.

McGregor is likely to next face Filipino icon Manny Pacquiao in the boxing arena, with the UFC hero telling Sportsnet "it's almost a certainty" and a contract is being drawn up.

McGregor's greatness in mixed martial arts is undisputed - The Notorious has a 22-4-0 UFC record - but Teixeira thinks his boxing aspirations are ridiculous.

"I don't hate Conor, I have nothing personal against him; I just think he hasn't learned yet that he needs to start from the bottom," Teixeira said.

"He wants to fight big as he did with Mayweather, now he wants Pacquiao. We who are on a higher level kill him easily without a problem, and he will be ashamed on TV.

"I would ruin his career, and he would understand that boxing is for real men, not for clowns. He could never take a fight like that. Floyd was nice to him, I wouldn't be."

Emerging Australian boxer Tim Tszyu, who defeated New Zealander Bowyn Morgan with a stunning knockout blow inside two minutes in December, had been hoping to challenge Teixeira for the WBO super welterweight title this year.

But that isn't looking as likely after Teixeira indicated he was hell-bent on meeting McGregor.