Sir Richard Branson has fanned the flames of a long-running feud with the boss of British Airways, calling on Willie Walsh to settle a "very public and painful" £1 million bet.
The billionaire founder of Virgin Group is claiming victory after pitching the wager to Mr Walsh in 2012 that Virgin Atlantic would still exist in five years' time.
However, the chief executive of BA-owner IAG refused to cede defeat, claiming the serial entrepreneur is the loser because he "no longer owns or controls the business" after giving up majority ownership earlier this year.
The initial terms of the bet were for the loser to pay £1 million bonus to the rival airline's staff, but Mr Walsh wanted to shift them to a "knee in the groin".
Writing on his Virgin blog, Sir Richard said it was time for the pair "to settle this matter once and for all".
He said: "Five years ago today, BA chief Willie Walsh wagered me a very public and painful bet. He bet that the Virgin Atlantic brand would disappear within five years. I disagreed.
"He said that the loser should accept a 'knee in the groin'.
"Although people might be amused to see me give Willie a low blow, I ideally have no wish to do so.
"So to settle this matter once and for all, and in the spirit of Christmas, I suggest he donates £1 million to Virgin Atlantic's team.
"If he doesn't agree then we'll just have to agree a time, date and place for the knee in the groin.
"Once this is over (one way or the other), lunch or dinner is on me, Willie, and perhaps we can draw a line under the past."
Sir Richard claims the public spat harks back to 1993 when BA was forced to apologise and stump up £500,000 to the billionaire - and a further £110,000 to his airline - following a libel battle.
However, the Virgin founder devised the bet 19 years later after Mr Walsh told reporters he thought Virgin Atlantic could disappear after Delta snapped up a 49% stake in the airline.
Since then, Air France-KLM bought a 31% stake in the airline in July, leaving Virgin Group with a 20% share of the business.
Responding to Sir Richard's latest blog post, Mr Walsh said: "When Richard Branson sold out to Delta five years ago, he said he would never give up control.
"As everyone knows, he no longer owns or controls the business, a reality confirmed by the decision to sell more of his shares to Air France. He's lost the bet."