A gambler known as the Fat Man has won his appeal against a High Court ruling to pay back a £2m debt amassed in just one night at a London casino.
Mr al-Zayat had demanded a change of croupiers
Businessman Fouad al-Zayat, a regular at Aspinall's, lost £23m over 12 years.
After a dispute during his biggest loss in March 2000, Mr al-Zayat dishonoured a cheque for £2m worth of gaming chips.
A judge ruled he had an arguable court case as Aspinall's delay of almost six years before trying to sue him for the money was an unlawful offer of credit.
Row over croupiers
The High Court ruling in March ordered Mr al-Zayat to settle the £2m debt plus legal costs because he had no realistic defence if the case went to trial.
But on Friday, three judges allowed the appeal, meaning Mr al-Zayat can now challenge the debt at a trial.
Aspinall's is considering an appeal to the House of Lords.
The row broke out at the club after Mr al-Zayat asked for a change of croupiers but was told none were available.
Later that night, he became angry when he found out there had been staff who could have taken over.
He demanded four house cheques to be returned and claims Aspinall's accepted his own cheque on the understanding it would not be cashed until their dispute was settled.
The gambler then told his bank not to honour the cheque and claimed in court it represented credit which is unlawful under the Gaming Act.
Lord Justice Sedley said: "Piqued at the club's failure to change a croupier, Mr al-Zayat, although he was undoubtedly good for the amount, dishonoured a cheque for £2m which he owed Aspinall's for gaming chips.
"Aspinall's, instead of burning their bridges with Mr al-Zayat by suing him on his cheque, permitted him for another six years to go on gambling so that he could lose millions more pounds to them.
"Then, at the last permissible minute, they sued him."
Fellow judge, Lord Justice Lloyd, said the action was brought only three days before the end of the six-year limit for a claim on the cheque.
In that time, Mr al-Zayat carried on gambling at Aspinall's and lost another £10m, he said.
Lord Justice Sedley said he would allow the appeal but said it was one of those cases "which have everything to do with law and nothing to do with justice".