Lowry was hurt while going for an offensive rebound when he flipped backward over the Nets' Quincy Acy. He got up and went back down with pain in both his back and legs, so much so that teammates trying to carry him off the court had to stop because it appeared Lowry was hurting too much.
The Raptors announced that Lowry has been diagnosed with a bruised tailbone and back spasms. He will not play in Tuesday's game against the Miami Heat and is considered day-to-day.
"We rely on Kyle for everything he does for us, to be the general out there on the court," said Raptors teammate DeMar DeRozan, who had 35 points in the win. "And it's tough when he's not out there, but we got to figure it out."
Lowry had 18 points and 11 assists before exiting.
"He reminds me a lot of Gary Payton, who threw his body around and he has to play that way to be effective," Raptors coach Dwane Casey said. "And we love it when he does because he was in there, getting rebounds over their guards and he got clipped on that one and hopefully he's OK."
Information from The Associated Press was used in this report.