The Chelsea Football Club owner, Roman Abramovich, has unleashed his most withering personal attack yet on his former business associate Boris Berezovsky, almost three months into the £3.5bn trial between the two men.
At the beginning of two days of closing submissions at London's Commercial Court, Mr Abramovich's barrister, Jonathan Sumption QC, called Mr Berezovsky an "angry and embittered man" with "truly prodigious powers of self-deception".
Mr Berezovsky is suing Mr Abramovich for more than $6bn (£3.5bn), claiming he was forced to sell his shares in valuable oil and aluminium businesses at a knockdown price, or face their re-appropriation by Putin's Kremlin, for whom Mr Abramovich acted as a messenger and enforcer.
The two Russians again sat on opposite sides of the court as Mr Sumption, the country's leading lawyer, delivered his final closing speech before being elevated to the Supreme Court bench next year.
"Mr Berezovsky was a persistently and deliberately untruthful witness," he told Mrs Justice Gloster. "There are so many occasions when he can be shown to have made up the facts in which he had no positive belief or which he positively knew to be false, it is simply not possible to take his word for anything."
Mr Sumption said many of Mr Berezovsky's allegations had been done "for show," because he "wants to make a point against the Russian government, he wants to discredit Mr Abramovich who he believes, in fact wrongly, to have supplanted him by occupying the sort of position in the Kremlin of Mr Putin that Mr Berezovsky himself once occupied under Boris Yeltsin."
Comparing Mr Berezovsky to Owen Glendower in Shakespeare's Henry IV Part 1, he said: "Mr Berezovsky has found it very difficult to accept that, for all his former importance as a power broker and for all the great wealth that he has obtained by that means, in business terms he was a relatively marginal player. He has a constant and palpable desire to portray himself as the central indispensable figure in every venture that he has touched."
Mr Berezovsky, who has sat patiently through almost every day of the lengthy trial, missed small amounts of the proceedings as he paced the corridors outside, talking loudly on his phone in English and Russian.
Mr Abramovich maintains the billions of dollars he paid to Mr Berezovsky was for krysha – the Russian word for roof – in this case meaning in return for both physical and political protection, and that Mr Berezovsky never held a genuine ownership stake in the oil and aluminium business.
Mr Berezovsky's barrister, Laurence Rabinowitz QC, will make his closing speech next month.