Two Russian oligarchs are squaring off in a London courtroom in a multibillion dollar lawsuit over an oil deal.

Self-exiled Russian tycoon Boris Berezovsky is suing fellow oligarch and former business associate Roman Abramovich.

Berezovsky's 2 billion pound ($3.3 billion) lawsuit claims Abramovich intimidated him into selling shares in Russian oil company Sibneft at a fraction of their value. Berezovsky is alleging breach of trust and breach of contract.

The case opened Monday and is expected to last two months. Both men appeared in court - and sat on opposite sides of the packed room.

Abramovich, owner of Chelsea Football Club, sold Sibneft to Russia's state-owned gas monopoly Gazprom in a multibillion-dollar deal in 2005.