Chelsea Football Club owner Roman Abramovich lost a bid to dismiss a £2 billion claim against him by fellow Russian oligarch and former business partner Boris Berezovsky today.
High Court judge Mr Justice Colman, refusing an application to strike out the action, said: "I am satisfied that it is impossible to say that his claim has no real prospect of success.
"Whereas in certain respects it may appear to present very formidable difficulties, it is in no respect so weak that Boris Berezovsky should be prevented from bringing it to trial."
Mr Berezovsky is alleging that Mr Abramovich used "threats and intimidation" to force him to sell shares in Russian oil company Sibneft at a fraction of their value.
These threats included pressure from Mr Abramovich that if the shares were not sold, they would be expropriated by the Kremlin, according to the claim.
In 2005, Mr Abramovich sold Sibneft to state-run OAO Gazprom for £8.5 billion.
The two men, who were once business partners, are among the richest in the world - but Mr Berezovsky's estimated £500 million fortune is dwarfed by Mr Abramovich's £10.8 billion.
Mr Berezovsky fled to the UK in 2000 after falling out with the then Russian president Vladimir Putin.