Chelsea Football Club owner Roman Abramovich "betrayed and blackmailed" fellow Russian oligarch Boris Berezovsky and demonstrated that wealth and influence meant more to him than loyalty and friendship, a barrister has alleged in the High Court.
Mr Berezovsky is claiming that Mr Abramovich "intimidated" him into selling shares in Russian oil company Sibneft at a fraction of their value.
He is alleging breach of trust and breach of contract and claiming more than £5 billion US dollars (£3.2 billion) in damages from Mr Abramovich, a judge was told.
Both men were at the first day of the trial - expected to last for more than two months - before Mrs Justice Gloster at the Commercial Court in London.
They sat at either end of the packed courtroom.
Laurence Rabinowitz QC, for Mr Berezovsky, told the judge that both men had worked together to acquire Sibneft and became friends.
He said Mr Berezovsky had been "betrayed" after falling out with Russian political leaders and leaving Russia in 2000.
"This is a case about two men who - and this is common ground - worked together to acquire an asset - that is Sibneft - that would make them wealthy beyond the wildest dreams of most people," said Mr Rabinowitz.
"In the process, we say, (they) became and remained good friends until, that is, Mr Berezovsky, who had adopted a high political profile in Russia, not least through his control of certain media outlets, fell out with those in power in the Kremlin and was forced to leave his home and create a new life abroad."
He added: "It is our case that Mr Abramovich at that point demonstrated that he was a man to whom wealth and influence mattered more than friendship and loyalty and this has led him, finally, to go so far as to even deny that he and Mr Berezovsky were actually ever friends."
