Allegro in F minor
This unfinished piano piece appears to have been intended as a movement in sonata form, and breaks off at the start of the development section. The manuscript score, comprising just 173 bars, is now preserved in the Klin House-Museum Archive (a1, No. 124).
The extant portion of the Allegro was published in volume 58 of Tchaikovsky's Complete Collected Works (1967), edited by Irina Iordan. There are also two later completions:
- By Konstantin Kalinenko as "Sonata in F minor" 
- By Leslie Howard, as "Piano Sonata No. 1".
In 1867 Tchaikovsky re-used the middle section of the Allegro in the Scherzo (No. 2) of the piano cycle Souvenir de Hapsal.