A draft manuscript of Tchaikovsky's Orchestral Suite no.2 Op. 53 could sell for £250,000-300,000 ($378,668-454,402).
It's set to provide the lead lot of Sotheby's Music, Continental and Russian Books and Manuscripts sale in London on May 28.
The suite was composed at Tchaikovsky's brother's home outside Moscow in the summer of 1883 and was first performed the following year in 1884.
Sotheby's explains: "Autograph musical manuscripts by Tchaikovsky are of the greatest rarity at auction.
"Moreover, this working draft contains major parts of an orchestral work (American Book Prices Current does not record any such manuscript by Tchaikovsky, apart from a single page sold here in 1995)."
Another handwritten manuscript, this time by Rachmaninov, carries a similar estimate of £200,000-300,000 ($302,935-454,402).
Titled The Symphonic Dances for Two Pianos, it was critically acclaimed on its debut. Sotheby's comments: "The first performance of this version was given by the composer and Vladimir Horowitz in Beverly Hills in 1942.
"Rachmaninov's biographer Sergei Bertensson was present at this occasion and wrote: 'The brilliance of this performance was such that for the first time I guessed what an experience it must have been to hear Liszt and Chopin playing together, or Anton and Nikolai Rubinstein'."
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