Paul originally injured his shoulder in Game 1, but he appeared to injure it again while battling for a rebound with Wesley Matthews.
It would be a massive blow for the Suns, even though they held a 30-point halftime lead against the Lakers in Game 5.
If Paul is unable to play in the rest of the game or series, it certainly would benefit the Lakers.
Paul had nine points, six rebounds and four assists while shooting 3-for-9 from the field before exiting.
The Lakers still trail the Suns big, as they were down 80-50 with 4:30 remaining to play in the third quarter.
The winner of Game 5 will need just one more win to take home the series and advance to the second round.