The Chelsea FC owner, one of the richest and most private men in the world, was accused of black-mailing Boris Berezovsky into selling his interests in the oil company and aluminium conglomerate they founded together at a knock-down price.
Mr Abramovich in turn, accused Mr Berezovsky of extorting money from him for political influence and claimed he had paid him $1.3bn to buy his freedom when Mr Berezovsky fell out of favour with Russian president Vladimir Putin.
In a year-long case that became highly personal, one of Mr Abramovich’s associates even accused Mr Berezovsky of sending a threatening text message to a potential witness, signed “Dr Evil”, the pantomime villain from the James Bond spoof films, Austin Powers. The message was never produced.
Mr Abramovich’s lawyers also accused Mr Berezovsky of “truly prodigious powers of self-deception” and giving evidence coloured by his “vanity and his self-obsession.”
They claimed that Mr Berezovksy was an “angry and embittered man” of “remarkable vanity and self-importance” which was “aggravated by a highly personal resentment of Mr Abramovich.”
“Large parts of his evidence can only be described as mendacious and dishonest,” they said in submissions to the court.
“He believes that Mr Abramovich has supplanted him in a position which is rightfully his and that he has acquired a sort of political influence under President Putin which he once enjoyed under a very different regime of Boris Yeltsin.”
Mr Berezovsky was once a “classic power broker” and one of the most influential oligarchs in Russia but the relationship was founded on krysha - political protection – and “the activities of a krysha or protector are inherently corrupt,” Jonathan Sumption QC, for Mr Abramovich, said in a written statement.
Mr Berezovsky "thought he had personally created Mr Abramovich out of nothing and put him in a position where he had only to sit there for vast sums of money to flow into his lap,” he added.
Laurence Rabinowitz QC, for Mr Berezovsky, had told the court that the two men had worked together during the Russian privatisation sales in the mid-1990s that followed the fall of communism to acquire an asset that would make them “wealthy beyond the wildest dreams of most people.”
In the process they “became and remained good friends” he said, but they fell out when Mr Berezovsky, who had adopted a high political profile in Russia through his control of a television station called ORT, fell foul of the Kremlin and was forced to leave the country and seek asylum in Britain.
The television channel had run a number of stories criticising Mr Putin for the failure to rescue 118 Russian sailors from the sunken nuclear submarine, the Kursk.
That, he said left Mr Abramovich in a position where he was “in effect required to make a choice - to remain loyal to Mr Berezovsky, his friend and mentor and the person to whom he owed his newly acquired great fortune, or instead, as we submit, to betray Mr Berezovsky and to seek to profit from his difficulties.”
“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,” he added.
The case rested on a number of key meetings at the end of 2000 in which the two men and a third partner, Badri Patarkatsishvili, a Georgian businessman who died at his Surrey mansion three years ago from a heart attack, discussed transferring their assets to the West.
Security men working for Mr Patarkatsishvili secretly recorded the first meeting at Le Bourget airport near Paris and Mr Berezovsky later bought the tape for $50m.
At the second meeting, at Mr Berezovsky’s chateau near Cap D’Antibes in France, Berezovsky claimed that Mr Abramovich told him the Kremlin would remove his TV station from him if he did not sell it and prevent the release from jail of a close friend of Mr Berezovsky.
Mr Abramovich claimed there was no such meeting and the pair actually met at the French ski resort of Megeve a few weeks later and agreed to a $1.3bn pay-off.
In a last snub to Mr Berezovsky, Mr Abramovich allegedly sold his 25 per cent share of the company Rusal, the Aluminium conglomerate, for £1bn, to Oleg Deripaska, an oligarch with ties to both George Osborne, the shadow chancellor and Peter Mandelson, the former Labour spin doctor.
The sale meant Mr Deripaska owned 75 per cent of the company and Mr Berezovsky and his partner were forced to accept just £289m for the remaining 25 per cent.