Russian media mogul Alexander Lebedev, who owns two UK newspapers, has punched a fellow guest off his seat during a televised economic debate in Moscow.
Mr Lebedev, owner of the Independent and Evening Standard, hit former real estate businessman Sergei Polonsky with two right hooks, sending him off the back of the platform.
Mr Lebedev said Mr Polonsky had been aggressive throughout the debate, which is to be aired on NTV on Sunday.
"I neutralised him," Mr Lebedev said.
Just prior to the attack, Mr Polonsky told the other guests he wanted to "stick one in the mouth".
Mr Lebedev stands, turns to the audience and then sits back down, only to launch immediately into a two-punch attack that sends Mr Polonsky sprawling.
Mr Lebedev, who also owns a major stake in the Russian newspaper Novaya Gazeta alongside former Soviet leader Mikhail Gorbachev and is the largest private share holder in Aeroflot, used his blog to try to justify the assault.
"In a critical situation, there is no choice. I see no reason to be hit with the first shot. I neutralised him."
Mr Polonsky did not appear to be harmed but pictures posted later online appeared to show a cut arm and torn trousers.
The BBC's Steve Rosenberg in Moscow says Mr Polonsky is considering legal action.
But Mr Polonsky's complaint about ripped trousers drew short shrift from Mr Lebedev.
"Now he's showing his ripped pants, and it is hard to say anything about that. He was hit in the face and he's showing off a hole in the backside of his trousers. Strange," Mr Lebedev wrote.
Mr Polonsky headed the Mirax Group, worth $1.2bn in 2008, but it was hit hard by the financial crisis and had to stop construction.
He once said: "Those who don't have a billion can go to hell."