In the 1990s following the collapse of communism, “quite extraordinary conditions” prevailed in Russia and it was impossible to get anywhere in business without political influence, lawyer Jonathan Sumption told the court.

On the second day of a British court battle, Sumption admitted Abramovich depended on Berezovsky’s links during this period and paid him $2 billion (1.5 billion euros, £1.3 billion) between 1995 and 2002 for his patronage.

He acknowledged that Berezovsky, who lives in exile in Britain, helped in the acquisition of oil company Sibneft but strongly denied his billionaire client owed his former patron damages over the sale of its shares.

Kremlin critic Berezovsky, 65, is suing Abramovich, 44, for more than $5 billion in damages at the Commercial Court in London, claiming the Chelsea owner intimidated him into selling Sibneft shares at less than their true value.

Abramovich is also accused of breach of trust and breach of contract in the trial, which is expected to last more than two months. He denies the allegations and disputes that “oral agreements” were made.

Both men were in court Tuesday, with large entourages of lawyers and bodyguards packing out the courtroom.

Berezovsky was animated during the hearing, chatting frequently to his legal team, while Abramovich sat in silence most of the time listening to proceedings through headphones.

Sumption described Berezovsky as Abramovich’s “political godfather”, conceding that without the elder oligarch’s influence Abramovich “would have got nowhere”.

Berezovsky controlled a “powerful media empire” and was close to people in then president Boris Yeltsin’s inner circle, said the lawyer.

By the late 1990s, Abramovich’s companies were paying Berezovsky’s “exuberant” expenses, which included palaces in France, private aircraft, and valuable paintings, he said.

“Mr. Berezovsky persuaded the Russian government to sell the right to manage Sibneft on the state’s behalf under an auction procedure which was easy to rig and was, in fact, mainly rigged by Mr. Berezovsky himself,” said Sumption.

“His contribution was important, indeed it was indispensable. But it was almost entirely political.”

Abramovich “always recognised that he would have to pay Mr. Berezovsky,” added Sumption. “He owed Mr. Berezovsky a great deal.”

But the lawyer said Berezovsky contributed nothing to acquiring or building up Sibneft, and neither did he make any managerial contribution.

He added that the Chelsea owner’s case is that the majority of Sibneft’s shares “were (indirectly) owned by him through companies he controlled.”

Berezovsky fled to Britain in 2000 after falling out with then-president Vladimir Putin and was granted political asylum in 2003.