A man was slashed from behind while playing chess in Union Square on Sunday morning, according to cops and sources. 

The 62-year-old chess player was sitting down at a table in the park’s locally famous game area when a person snuck up and cut him along the back, police and law-enforcement sources said. 

The assailant then ran away on foot, cops said. 

Cops said it’s unclear why the assailant slashed the player and if the incident was chess-related.

EMS rushed the wounded man to Bellevue Hospital, where he is in stable condition, according to authorities. 

Union Square is known for its chessboards, where players take on passers-by in games, often with money wagered.