Former Herbert Smith senior partner Lord David Gold has been brought in to advise Chelsea FC owner Roman Abramovich on the multibillion-dollar lawsuit brought against him by Russian businessman Boris Berezovsky.

Gold (pictured) is understood to have been brought onto the case after Abramovich's second attempt to have the proceedings struck out was rejected in the Court of Appeal in February this year.

The case relates to a claim by Berezovsky that he was coerced by Abramovich to sell his stake in Russian oil company Sibneft at a significant undervalue, and that Abramovich sold Berezovsky's shares in Russian aluminium company Rusal without his consent.

Following the Court of Appeal's decision earlier this year, Abramovich is understood to have instructed Gold to help with running the case and preparing him and the witnesses for trial.

Gold set up litigation boutique David Gold & Associates in March this year after leaving Herbert Smith at the end of February. Rather than taking the lead in litigation cases, the boutique works alongside its clients' existing solicitors as an additional resource.

Brick Court Chambers Jonathan Sumption QC is also acting for Abramovich alongside Skadden Arps Slate Meagher & Flom litigation partner Karyl Nairn, international arbitration partner Paul Mitchard QC and of counsel Rory McAlpine.

Skadden's Bruce Buck, the partner-in-charge of the US firm's European offices, is Chelsea FC chairman.

Brick Court Chambers' Andrew Popplewell QC acted for Abramovich at the Court of Appeal hearing earlier this year, before the case was handed to Sumption, after Popplewell's appointment as a High Court judge was announced in August.

One Essex Court's Laurence Rabinowitz QC is acting for Berezovsky alongside Addleshaw Goddard litigation partners Mark Hastings and John Kelleher.

The case is currently being heard in the High Court and is understood to be the highest-value claim being litigated in the world, with press reports estimating its value at as much as $6.5bn (£4.1bn).

The trial began on 3 October this year and is the first case to be heard in the new Rolls Building.

The news follows Sumption's appointment to the Supreme Court in May this year. Sumption has delayed his start date at the Court while he finishes his work on the Abramovich case, causing some controversy at the Bar.