The World Conker Championships is investigating after the men's champion was found with a steel chestnut in his pocket.
David Jakins, 82, was victorious in Sunday's event - it was his first win after competing since 1977.
The veteran player, known as "King Conker", recorded several victories in which he destroyed the other player's conker with one hit.
His opponent in the final Alastair Johnson-Ferguson told The Daily Telegraph he raised concerns after his conker "disintegrated in one hit, and that just doesn't happen".
A fake steel conker, painted brown, was later found in Mr Jakins' pocket.
He denied using it during the tournament in Southwick, Northamptonshire, and said he only had it with him for "humour value".
Mr Jakins, who helped prepare other players' conkers which are selected randomly from a sack, also denied any suggestion he marked the strings to highlight harder nuts.
The chairman of the organising committee said the steel conker was indistinguishable from a real one, with its weight the only giveaway.
St. John Burkett told Sky News that an investigation of a video suggested no foul play and that Mr Jakins had called the cheating claims "a load of nonsense".
"We are currently minded to think that the win was fair, and that the steel conker was kept in the pocket throughout, but just need to complete the last parts of the investigation," he said.
He told Sky's Kay Burley: "Whilst Mr Jakins put his hand in his pocket at the end of the match and indeed threw a conker from a different pocket into the crowd, he was very closely watched by four judges.
"It looks like it was absolutely impossible for him to cheat. We have got some various other testimony that indicates innocence."
Mr Jakins won the men's competition but lost in the overall final to women's champion Kelci Banschbach, originally from the United States, who only took up the game last year when she moved to Suffolk.
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The championships have been held since 1965 and organisers say they have raised £420,000 for charity.
This year's knock-out event, at the Shuckburgh Arms, saw a host of interesting competitors take part in front of an enthusiastic crowd.
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