Parker tumbled to the baseline after a hard drive to the basket in the third quarter, and immediately began writhing on the ground. Television replays showed Parker awkwardly plant his foot during the drive.
The Spurs said X-rays were negative and Parker did not return to the game. They will likely know more Thursday about when Parker will be ready to play.
"We're going to have to adjust to it," said Tim Duncan, who grabbed a career-high 27 rebounds and scored 21 points in the win. "We're trying to get something going here and then we lose Tony. We'll find a way to get it done."
Parker missed several games earlier this season after spraining his left ankle Nov. 6. He has also been struggling with plantar fasciitis in the same foot all season.
Parker is the second-leading scorer for the Spurs, averaging 17.1 points.
Information from the Associated Press was used in this report