Lowry suffered the injury in Toronto's 122-104 win over the New Orleans Pelicans on Friday night. He went to the bench after he was hurt but returned a few minutes later. He made two 3-pointers in the second quarter before subbing out midway through the period and retreating to the locker room.
The Raptors also lost Serge Ibaka to injury Friday. He sprained his right ankle contesting a layup in the second quarter and will be out indefinitely, the team said.
Ibaka will undergo more imaging while the Raptors are in Los Angeles as part of a five-game trip.
Lowry is averaging 21.8 points and 6.5 assists per game. Ibaka is averaging 14.0 points and 6.5 rebounds.
The Associated Press contributed to this report.