Kristaps Porzingis left Game 4 of the Boston Celtics' first round series against the Miami Heat with a non-contact injury.

The Celtics publicly announced Porzingis was doubtful to return with right calf tightness.

Sources tell ESPN's Adrian Wojnarowski that the early indications are Porzingis did not sustain an injury to his Achilles. 

When a player tears his Achilles, it is typically a fairly obvious immediate diagnosis.