The High Court has refused to halt a legal battle over the ownership of an original Rachmaninov manuscript, due to be auctioned last December.
Rachmaninov left Russia in December 1917
The Russian composer's score for his Second Symphony was expected to fetch around £500,000 at the Sotheby's sale.
But the 300-page work was withdrawn after members of Rachmaninov's family claimed to be the true owners.
Sotheby's sought to have the case dismissed but a judge ruled both sides could win so the case must proceed.
The family of Rachmaninov say there is no evidence of the composer having sold the manuscript during his lifetime.
Sotheby's have said it is likely that Rachmaninov, who died in 1943, disposed of the manuscript voluntarily during his lifetime.
According to a biography of the composer, the work was completed in Dresden, Germany, in 1908. He fled Russia nine years later, with only one small suitcase in his possession.
The manuscript was found in a cellar in Switzerland after being lost for almost a century. It has several pages missing, including the title page, and was one of a few of his original scores to be lost.
The person selling it was a "European private collector", according to Sotheby's, but the company would not give further details.
Mr Justice Tugendhat rejected a bid by Sotheby's to prevent the composer's family from taking legal action, which they claimed would have no prospect of success.
He said it was possible that Rachmaninov had left the manuscript in Russia or Germany, and it was possible that it had been owned by a person who received it for safekeeping and intended to return it to the composer one day.
This was based on evidence that Rachmaninov had written to his sister-in-law saying that the manuscript of the First Symphony was left in his desk in Russia and its safety had been entrusted to a housekeeper.