Atlanta says Smith won't travel with the team. There was no mention of the injury after Smith played 41 minutes in the Hawks' season-opening 109-102 loss to Houston on Friday night.
The Hawks said on Saturday that Smith was injured during the game. Smith had 18 points, 10 rebounds and three blocked shots against the Rockets.
Smith set career highs by averaging 18.8 points and 9.6 rebounds last season.
The Hawks say backup center Johan Petro will also miss Sunday's game because of a lower back injury. He wasn't in uniform on Friday night.