Kyrie Irving left Game 4 of the Eastern Conference Semifinals with a right ankle sprain and exited the area using crutches and in a walking boot.
Irving suffered the injury during the second quarter. X-rays on Irving's ankle were negative.
The Brooklyn Nets are already without James Harden due to a hamstring injury.
"I have no idea what is going to happen with Ky in the coming days," Steve Nash said. "We will cross our fingers and hope that it is better than I don't know -- better than what -- better than missing the next game?"