Nelson suffered the injury as he drove against Darren Collison with 4:49 left in the game and suddenly attempted to stop quickly. Nelson crumpled to the floor, and Collison forced a jump ball.
Nelson didn't return to the game.
"I still have to do the evaluations," he said afterward. "I think it should be OK just by the way it's feeling. I don't want to make an assessment on it right now without getting fully evaluated by the doctors and getting all the MRIs and all that stuff I have to get probably. Hopefully, it's not too serious and I can move forward."
Nelson offered some humor when he was asked what, exactly happened.
"I'm so quick I don't know what happened," he joked. "Nah, I made a move and it was a weird feeling. My knee gave out, and when it gave out, I fell and banged it on the ground. So it was like a double-whammy."
The Magic medical staff wrapped ice around the knee after the game.
Nelson has missed 11 of Orlando's 54 games this season.