Bluebird Pas de Deux is a 1941 arrangement for chamber orchestra of a short section of Pyotr Ilyich Tchaikovsky's The Sleeping Beauty composed by Igor Stravinsky.
Though, initially, Tchaikovsky intended this to be a pas de quatre, Marius Petipa changed it in the original production, hence Stravinsky's title.
However, in the case of Bluebird, Stravinsky had to adapt to the company's orchestra's condition, as it had been depleted by the military draft just months before the US involvement in World War II.
[5][4] As an original addition, Stravinsky did not actually reduce the orchestra, but rather chose to include a piano to provide a new element to help articulation and sonority.
[1] According to Stravinsky himself, "the prominent piano part [...] helps to conceal the small number of strings" in Bluebird Pas de Deux.