An investment banker who is suing Newcastle United owner MikeAshley after claiming that he is owed £14 million has been accused of making up evidence.
Jeffrey Blue says Mr Ashley, who also runs Sports Direct, did not stick to a commercial agreement.
Mr Ashley disputes the claim and a judge is analysing evidence at a High Court trial in London.
Mr Justice Leggatt has heard that the dispute between Mr Blue and Mr Ashley relates to a conversation in a London pub in 2013.
Mr Blue says Mr Ashley made a promise during a meeting in a London pub called the Horse & Groom.
He says Mr Ashley promised to pay him £15 million if he used his expertise to increase Sports Direct's share price to £8 a share. He says Mr Ashley paid only £1 million.
Mr Blue came under attack from Mr Ashley's lawyers as he gave evidence during the second day of the hearing on Tuesday.
Barrister David Cavender, who is leading Mr Ashley's legal team, accused Mr Blue of "making up evidence".
Mr Ashley, who is due to give evidence on Wednesday, watched from the back of the court as Mr Blue was questioned by Mr Cavender.
Mr Cavender has described Mr Blue's claim as an "opportunistic try-on".
"The claim appears to have been issued on the basis that the threat of negative press alone would compel Mr Ashley to settle," he has said in a written outline of Mr Ashley's case.
"In truth, there was no purported agreement and Mr Blue could not have thought so at the time."
Mr Cavender said Mr Ashley "fairly" said he could not recall details of conversations in the Horse & Groom "particularly in the light of the amount of drinking".
"He does recall 'that there was a lot of banter and bravado'," said Mr Cavender.
"He does not recall any discussion about whether Mr Blue would be paid a sum of money if the share price reached £8 a share."
Mr Cavender added: "He says if there was 'it would have been obvious that he was joking'."
Mr Ashley has told the judge, in a written statement: "I can't believe that (Mr Blue) is now trying to take me for £14 million off the back of some drink banter that he is seeking to engineer
into something more."
Mr Blue has told the judge how he saw Ashley vomit into a fireplace after a Sports Direct senior management meeting which was ''effectively a pub lock-in''.
He has told how the Sports Direct boss would also nap under tables at "boring" meetings.
The hearing continues.