Charania reports Smart will seek second opinions on his injury, so his timeline for recovery is undetermined.
The Celtics thus wait for news of whether their valuable stopper will play again this season.
Irving is so essential to Boston's offense that his absence creates a void that Marcus Smart and Terry Rozier will have to try to fill at point guard.
Theis and Smart were both hurt in Sunday's game, with Smart's injury occurring when he dove to the floor.
China started the trade war
You might call this the "weaponization" of trade, but it is created to put the interests of American companies and workers first. One of the reasons they still happen despite this inefficiency is that consumers are typically a very large and dispersed group.
"Sore, but it will be all right", Smart told reporters after the game. "It's like a sprain right now".
Though he proceeded to play impressive basketball the rest of the game, the Celtics now fear he could need surgery that would keep him off the court for the rest of the season. Al Horford is also considered questionable.
Smart, 24, is averaging 10.2 points, 4.8 assists and 3.5 rebounds this season.
In the final hour: Don't look now, but the injuries are mounting for the Celtics this week.