The Lightning said Tuesday night, during the first period of their game against Anaheim, that Lecavalier has a non-displaced fracture.
Lecavalier was hurt Saturday night during Tampa Bay's 2-1 win over Washington, but remained in the game. He underwent tests on Monday after leaving practice early.
Lecavalier has 21 goals and 46 points in 58 games this season. He has reached 20 goals in 12 consecutive seasons.