Newcastle United owner and sportswear firm boss Mike Ashley is preparing for a High Court fight with a finance expert.
Jeffrey Blue has sued Mr Ashley - detail of the case has emerged at preliminary hearings.
Judge Mr Justice Leggatt is due to start analysing evidence at a High Court hearing in London today.
Lawyers have said the dispute relates to an alleged conversation in a pub.
Judges have heard how Mr Blue said Mr Ashley, who runs Sports Direct, had made a promise during a meeting in a London pub called the Horse & Groom.
Mr Blue said Mr Ashley promised to pay him £15million if he used his expertise to increase Sports Direct's share price to £8 a share.
He said Mr Ashley paid only £1million. Mr Ashley disputes the claim.