Chelsea Football Club owner Roman Abramovich is "good at appearing to be humble", a High Court judge was told today.
Russian oligarch Boris Berezovsky - who says he was "betrayed" by Mr Abramovich following an oil firm deal and is claiming billions of pounds in compensation - said the billionaire Russian businessman was "good at getting people to like him" and "good at psychology".
Mr Berezovsky, 65, says Mr Abramovich "intimidated" him into selling shares in Russian oil company Sibneft at a fraction of their value.
He is claiming more than £3 billion in damages from Mr Abramovich - and alleging breach of trust and breach of contract - in a trial in the Commercial Court in London.
Mr Abramovich, 44, denies the allegations, disputes that "oral agreements" were made and denies Mr Berezovsky is entitled to damages.
Mr Berezovsky today started giving evidence to judge Mrs Justice Gloster as the trial, expected to last more than two months, entered its fourth day. Mr Abramovich watched from the public gallery.
"He (Mr Abramovich) is good at getting people to like him and good at psychology in that way," said Mr Berezovsky in a written witness statement given to the judge.
"He is good at appearing to be humble. He is happy to spend days just socialising with important or powerful people if that is what is needed so he can get closer to them."
Mr Berezovsky said he met Mr Abramovich on a cruise on a private yacht in the Caribbean in 1994 and was "very impressed".
"I formed a very favourable view of him," said Mr Berezovsky in his written statement. "He was a very charming person."
Mr Berezovsky said he was a "leading" Russian businessman when they met but Mr Abramovich was "in the early stages of his business career" and had "not made any serious money".
He said he came to regard Mr Abramovich as "my protege, as the next generation".
Mr Berezovsky said they discussed the creation of Sibneft and were "50:50" partners.
The plan was to combine two Russian oil firms into a single company which could be "privatised into our control".
He said each had "respective roles". He would conduct "all high-level discussions in order to persuade" President Boris Yeltsin's government to create the new company. Mr Abramovich would co-ordinate "his contacts in the oil sector".
"This agreement was very generous to Mr Abramovich because Sibneft would never have been established and included in the privatisation programme without my connections with President Yeltsin and the Government," said Mr Berezovsky.
"I believe if it had not been for the considerable effort I put into the Sibneft project and the considerable political capital I expended it would never have come to fruition."
He added: "My input was decisive in the creation of Sibneft."
Mr Berezovsky said Mr Abramovich "insisted that our agreement should not be written down" and "such oral agreements were simply common practice at that time between Russians in Russia".
"I understand that Mr Abramovich has denied the agreement we entered into regarding the ownership of what was to become Sibneft," said Mr Berezovsky. "I consider there is no basis at all for that denial."
Mr Berezovsky said he later agreed to "distance himself" from Sibneft because Mr Abramovich thought that "my political profile had the potential to have a detrimental effect".
But he said Mr Abramovich agreed that "(my) interests would be protected and that (my) share of the profits" would continue to be paid.
"I recall him saying to me," said Mr Berezovsky in the written statement, "'Boris, you understand that I will look after your interest. My interests are your interests, your interests are my interests'."
Mr Berezovsky said he left Russia in 2000 - after "falling out" with then president Vladimir Putin - and had not returned.
He said he met Mr Abramovich in France in December 2000 - at Le Bourget airport near Paris and at his then home in Cap d'Antibes - to discuss the implications of his "self-imposed exile" on their business affairs.
Mr Berezovsky told the judge that Mr Abramovich's political influence had increased and by 2000 his position with Mr Putin was "completely cemented" - and he said he had "begun to grow suspicious of Mr Abramovich".
"I remember being surprised by how integrated Mr Abramovich was, not only with the leadership of the Kremlin but also with the Prosecutor-General's office," said Mr Berezovsky.
"It was evident from what Mr Abramovich said to me during that (airport) meeting that he could get people out of trouble with the Russian state and he could also close down criminal cases."
And he told the judge that "taking away by financial interest" was "something Mr Abramovich had been pushing for".
"It was, finally, clear to me how ruthless Mr Abramovich was, and I had no doubt he would use any means necessary to achieve this, legal or otherwise," said Mr Berezovsky.
"I understood Mr Abramovich to be threatening that ... I could either sell (my) interest in Sibneft and receive some money (albeit at a gross under value) or he would ensure that (I) would lose my interest...
"He knew that, given his influence in the Kremlin ... (I) would understand, or at least, fear that he had the influence to bring this about."
He said he "knew he had no choice", and added: "I had no doubt that the state persecution and the seizure of (my) interest that Mr Abramovich threatened would happen if he wanted it to."
Mr Berezovsky told the judge of his "anger and frustration" at Mr Abramovich's "disgraceful behaviour", and said: "Mr Abramovich betrayed (me) despite the generosity (I) showed him."
The hearing continues.