Floyd Mayweather Jr offered a cutting response to the challenge of a rematch with Manny Pacquiao, dismissing the Filipino as his "employee".
Pacquiao (62-7-2) defeated WBA welterweight world champion Keith Thurman in Las Vegas last week, with Mayweather, who boasts a 50-0 record and beat his fellow great in 2015, in attendance.
But the American was not impressed by mention of him in reporting of Pacquiao's victory, prompting an incredible social media back-and-forth.
Mayweather first posted a lengthy message on Instagram, saying in part: "I find it real ironic how every time Pacquiao's name is brought up in the media, my name is always attached to it.
“This man's entire legacy and career has been built off its association with my name and it's about time you all stop using my brand for clout chasing and clickbait and let that man's name hold weight of its own.
“For years, all you heard was that 'Floyd is afraid of Manny Pacquiao'. But what's funny is, when we finally fought, I won so easily that everyone had to eat their words!”
That led to a response from Pacquiao on Twitter in which he appeared to ask for a rematch.
“@FloydMayweather, you come to my fight and then use my name in a post but I'm the one that is trying to stay relevant?" he wrote. "If you want to be relevant again... #MayPac2”
But Mayweather came back in devastating fashion.
The 42-year-old, who last fought competitively against Conor McGregor in 2017, took to Instagram again and wrote: "Bottom line, I make more money than you; I beat you, then I signed you!
“I was only at your fight supervising you, my employee, as any real BOSS would do. You made $10million for 12 rounds, when I just made $9m in under three minutes playing around in an exhibition with a pizza delivery guy!
“I beat you mentally, physically and financially! Remember, you fight because you have to, I fight when I want to!”
Mayweather knocked out Tenshin Nasukawa in an exhibition on New Year's Eve, with Pacquiao calling out his old foe three weeks later.
Pacquiao's camp have denied claims from Amir Khan the pair have agreed a fight in November.