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 $5bn (€3.74bn) 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 on Monday.
They sat at either end of the packed courtroom.