The NRL and Bulldogs launched court action against Williams yesterday for what they say is breach of a "watertight" contract. But Williams's lawyers will argue that the salary cap is an unreasonable restraint of trade - and some legal experts suggest he could succeed.

Williams was stuck in London last night, with visa difficulties delaying his move to France, but before he fled the Bulldogs last Saturday a leading Sydney barrister prepared a legal strategy to challenge the salary cap, which sets a ceiling of the total amount clubs can pay their players.

If Williams, 22, was successful it would represent the worst nightmare for Australia's four football codes, which all rely on caps to restrain player payments.

The Bulldogs star has been summonsed to appear next Tuesday at a hearing of the NRL's and Bulldogs' application for an injunction to prevent Williams playing or training with a rugby club in France - provided lawyers can find and serve papers on him in person before 6pm on Sunday, Sydney time. Williams's lawyers will say the Bulldogs can pay more than his existing $450,000-a-year contract but are prevented from doing so by NRL rules that create salary parity across its 16 clubs. Williams is expected to earn the equivalent of $3 million for two years with the French club Toulon.

Should an Australian court find in favour of the New Zealand international, it would entitle the AFL Players' Association to challenge the Australian rules salary cap, dismantling a club structure that has preserved a competitive balance for 30 years and prevented billionaires such as the Carlton patron Dick Pratt spending whatever they wanted to plunder the talent of rivals.

The Australian Rugby Union also imposes "contracting protocols" which set maximums on what its four Super 14 clubs pay players, an arrangement even more vulnerable because it was reached without the input of its players' association. Soccer's A-League has a salary cap in place, with a single marquee player allowed to earn full market value.

The player manager Steve Gillis warned that several more NRL stars are on the verge of leaving the game. "They're looking for our very best players," he said. "They'll knock them off one by LEAGUE IN CRISIS 'Extradition treaties for criminals are one thing; a process to bring back runaway footballers quite another.'

PETER FITZSIMONS Page 4 'This legal strategy could

end in the worst nightmare for Australia's three big football codes.'

ROY MASTERS Page 40 It got worse for the Bulldogs last night when the Dragons thrashed them 30-0 before an embarrassingly small crowd at ANZ Stadium. Page 38

by one. I think you'll find if there's four or five this year. There'll be 10 next year, probably 20 or 30 the next year. If Sonny Bill Williams is allowed to walk out on his contract and there's no rearguard action, I would expect that other players would want to follow suit."

The NRL chief executive David Gallop and the Bulldogs chief executive Todd Greenberg launched a legal campaign they warned may result in Williams's assets being seized and the player himself arrested or even jailed.

"Ultimately, if these proceedings were to reach the end conclusion and he was to ignore them, then he's facing criminal charges," Mr Gallop said. "He's liable to criminal charges which can involve arrest, can involve seizure of his assets in Australia."

But their first challenge is to find him, with the Supreme Court rejecting their bid for "substituted service" and forcing lawyers to serve the documents to Williams in person. The club had asked the court to allow it to serve Khoder Nasser, who it had believed was Williams's manager, or the Toulon club with the documents for Williams. But Justice Robert Austin, who said he had not heard Williams's side of the story, rejected the application, arguing that informing the French club of the allegations could do "irreparable harm" to Williams.

Mr Gallop said: "The sanctity of his contract is one of the reasons why he has conducted himself in such a secretive and deceitful way. If his contract was not watertight, he could have gone to the Bulldogs and said, 'I want out.' The clear assumption is that he has received advice that his best chance is to secretly and furtively leave the country and avoid service of a summons."

He admitted: "Of course the prospect of lucrative contracts being on offer overseas is a concern for us … It's far more difficult to come up with a foolproof solution."

The Supreme Court heard that Mr Nasser, who on Sunday told Channel Nine he was no longer Williams's agent, had been involved in discussions with the club as late as Saturday. Even on the day Williams was leaving the country, Mr Nasser had assured the club that Williams would continue to play for the Bulldogs.

Arthur Moses, barrister for the Bulldogs, said Mr Nasser's brother was travelling with Williams, and the boxer Anthony Mundine had taken him to the airport on Saturday. Mr Moses said the club had been deceived and hoodwinked by Mr Nasser.