Outspoken Ryanair boss Michael O'Leary faces a potential court battle with rival easyJet after publishing a newspaper advert depicting its founder Sir Stelios Haji-Ioannu as Pinocchio.
The advert centres around the publishing of easyJet's punctuality figures, which Ryanair claims are "missing" from the Luton based airline's website.
The Greek billionairehas accused O'Leary of libel and has threatened to go to the courts unless he receives compensation.
Sir Stelios said: "With this advert he went too far and I am obliged to draw the line here. This is a libel action about my own reputation as an individual, not about comparing the two airlines. He called me a liar, I am not a liar. That is libellous, and I will seek substantial damages.
"It was about time someone was willing to spend the money to take this arrogant man to court for his despicable behaviour... See you in court Michael."
Ryanair has accused easyJet of "hiding its poor on-time statistics (which have not been published on its website for the last 40 weeks in a row) because (Ryanair believes) easyJet's punctuality is so awful compared to that of Ryanair".
EasyJet, however, says it publishes its punctuality figures on an annual basis, in its annual report.
An easyJet spokesperson told ABTN: "Those results show we've made an improvement on last year. We're proud of those, we publish those, we've got nothing to hide."
But Sir Stelios said he has asked Sir Michael Rake, chairmain of the airline, to "start publishing them again".
"The relevant facts of the case are that I was not involved in the decision to cease publishing the statistics on the easyJet website. It has not been my job to design the website of the airline for over ten years," said Sir Stelios.
"As easyJet is listed on the stock exchange, the board will have to make its own decisions.... What the stats say or don't say about the two airlines is not the point. They are completely irrelevant for the outcome of this libel action."
To settle the dispute, O'Leary has challenged Sir Stelios Haji-Ioannou to a "Chariots of Fire" race around Trafalgar Square.
He said: "I am currently in rigorous training and believe that my daily regime of 40 cigarettes, 24 beers and extended sessions on the couch watching TV, leaves me in perfect shape to beat Stelios in a 21st Century version of the "Chariots of Fire" race around Trafalgar Square.
"We believe this race will be a much better use of Stelios' time rather than paying expensive lawyers to issue vacuous threats, when both Stelios and easyJet know they can't compete with Ryanair's prices and they can't match our punctuality either.
"If Stelios is too "tired" to run, then I will offer him the alternative of a wheelbarrow race around Trafalgar Square, with the winner taking all. Win or lose, at least Stelios and easyJet will save a fortune on expensive lawyers fees. No expensive lawyers can alter the facts, compared to Ryanair, easyJet is a high fares airline, and an always late airline. See you in Trafalgar Square Stelios!"
However, since O'Leary challenged Sir Stelios to the race, passengers have sent numerous other suggestions, including an arm-wrestling match, mud wrestling contest and drag race (dressed in high-heels and fishnets). Ryanair passengers can now vote online which one they think they airline bosses should do.