Conor McGregor has branded Jake Paul a "jackass" after the YouTube boxer criticised the UFC star's technique.
McGregor is currently completing his rehabilitation from the broken leg he suffered in his third fight with Dustin Poirier last summer.
He pulled on pair of boxing gloves last week and posted a clip of himself hitting pads.
Paul rushed to label McGregor's technique as "embarrassing" while former UFC champion Henry Cejudo was also critical.
Paul, who has amassed a professional boxing record of 5-0, has long angled for a fight with McGregor and went on to claim he would knock him out.
"I would KO Conor in boxing or MMA. Right hand of God," he said.
McGregor has been reluctant to engage with the 25-year-old but finally broke his silence hours later with a short video.
Replying to Paul's tweet, McGregor throws a combination of punches before saying, "jackass" and switching off his phone.
A fight between the two is some way becoming a reality as McGregor eyes a return to the top of the UFC.
He has pencilled in his return for the summer and has demanded a lightweight title shot despite not having won at 155lb since he beat Eddie Alvarez in 2016.
McGregor's only win in his last four fights was his 40-second demolition of Donald Cerrone in 2020.
He has two fights left on his UFC contract which would mean he could be available to fight Paul next year.
The social media star racked up three victories in the ring last year, two against Tyron Woodley and one against Ben Askren.
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He is taking a break from the sport to promote stablemate Amanda Serrano's fight against Katie Taylor on April 30.
But he plans to return in the summer - and could reschedule his ill-fated clash with Tommy Fury.
In another video, Paul added Jorge Masvidal's name to his hit-list following the welterweight's defeat by Colby Covington last weekend.
"A new saying is, I feel bad for stupid people, they're so stupid they don't even realise they're stupid," he said.
"It's like people who think Masvidal is a good fighter; it's like the people who think Conor McGregor is still a good fighter.
"These guys haven't won fights in I don't know how the f*** long. They're over the hill, washed-up bozos and I'm going to knock them both the f*** out."
