Jake Paul as called on Conor McGregor to throw his weight behind the YouTube star's battle for improved fighter pay.
Paul has been embroiled in a row with UFC president Dana White over the issues as he looks to improve conditions for stars in the leading MMA promotion.
And after middleweight champion Israel Adesanya announced his new UFC deal made him the second-highest-paid fighter in the promotion behind McGregor, Paul insisted he was still due more.
McGregor, who shares a management company with Adesanya, then congratulated his stablemate, saying: "Congrats Paradigm Sports Management Agency! Number 1 and 2 highest paid on the UFC roster contractually, myself and Izzy.
"An excellent feather in the cap of an amazing sports agency. Congrats to all my team and a big congrats last night Israel."
McGregor was referring to Adesanya's rematch victory over Robert Whittaker on Saturday night which saw him retain his belt.
Paul then replied to McGregor, tweeting: "Indeed well deserved for Izzy but but unfortunately Tyson Fury still makes more than both of you combined for fighting.
"Conor when you gonna start playing your part to get ALL fighters better pay and healthcare?"
Paul was referring to Fury's forthcoming purse for his world title defence against Dillian Whyte.
Fury's promoter Frank Warren won the bid with an offer of £31million, of which Fury will earn £25m if he successfully defends his title.
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McGregor is the only UFC fighter who comes close to earning as much as Fury, with most of his wealth now generated by his whiskey business.
And the gulf in pay cheques was never clearer than when UFC heavyweight champion Francis Ngannou earned $600,000 for his title defence against Ciryl Gane last month.
His purse paled into insignificance when compared to Fury's and is a major sticking point in Ngannou's contract negotiations with the UFC.
He has so far refused to sign a new deal unless his terms are improved - and he also wants a clause which allows him to take part in a boxing fight.
He and Fury have exchanged verbal jabs on social media over a crossover fight in 2022.
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