Boston Celtics center Kristaps Porzingis injured his right calf in the second quarter of Game 4 against the host Miami Heat on Monday and was listed as doubtful to return, per the team.

The Celtics announced that Porzingis, who exited with 2:27 left in the first half, was dealing with right calf tightness.

Boston beat Miami 102-88 to take a 3-1 lead in the best-of-seven, Eastern Conference first-round playoff series.

On the play in which he was injured, Porzingis caught a pass from Jaylen Brown and began to drive before giving it back to Brown and hobbling off the court and into the locker room. It didn’t appear that anyone made contact with Porzingis on the play.

Per ESPN, it didn’t appear that Porzingis injured his Achilles tendon. The veteran center reportedly will undergo testing on Tuesday.

Al Horford started the second half in place of Porzingis.

In his first season with the Celtics after an offseason trade, Porzingis has been a key piece to the team’s success, averaging 20.1 points and 7.2 rebounds per game in the regular season.

He had seven points and three rebounds in 14 minutes on Monday, dropping his playoff averages to 12.3 points and five rebounds per contest in the Miami series.