Boston's Kristaps Porzingis tries to pass the ball while double teamed by New York's OG Anunoby and Josh White during Monday night's Game 1 of their Eastern Conference semifinal series at TD Garden. (AP photo)

BOSTON (AP) — Celtics center Kristaps Porzingis didn’t play in the second half of Boston’s loss to the New York Knicks in Game 1 of the Eastern Conference semifinals because of an illness.

Porzingis wasn’t on the floor initially with the team Monday night as they warmed up prior to the start of the second half.

He came out of the tunnel and joined them briefly in the bench area, but then returned to the locker room. Al Horford started the third quarter in his place.

The Celtics announced Porzingis was questionable to return with an illness that they specified was non-Covid.

Reserve Sam Hauser also didn’t return after leaving the game early in the fourth quarter with a sprained right ankle.

Porzingis was 0 for 4 in 13 minutes of the first half, with four rebounds and an assist. Hauser missed both of his shots in four minutes of action.