Porzingis, who had missed the Mavericks' previous three games due to a sprained left ankle, complained of the soreness in his knee midway through the third quarter. The visiting Mavs announced at the start of the fourth that he wouldn't return.
"We'll hope for the best," said Mavericks head coach Rick Carlisle, who noted that Porzingis seemed to be walking fine after the team's 115-105 win over Detroit. "We'll hope that it's not any kind of a serious issue and go from there."
Porzingis had 11 points and one rebound in 21 minutes against the Pistons on Thursday night.
The 7-foot-3 Porzingis, who entered Thursday's contest averaging 20.4 points and 9.3 rebounds per game, has had surgery on both of his knees. He tore the ACL in his left knee in February 2018.
Porzingis has averaged 18.7 points and 7.9 rebounds per game in his NBA career.