The fact that he walked to the locker room under his own power was encouraging. And reports say he wanted to come back out, but the team held him out for precautionary reasons. I made this GIF of the exact moment of impact- it's obvious that he just tried to change direction very awkwardly, and the foot doesn't bend all the way. The twist of the ankle isn't parallel with the ground, like Greg Oden's injury on Tuesday night.
Putting on my doctor's cap: that looks like a mild right ankle inversion. It probably was a pretty painful injury, but he's now listed as day-to-day. I doubt he misses Saturday's Opener.