Just caught this from WWE's official Twitter feed (@WWE).
I had read that he left the traditional Survivor Series style elimination match early with an injury. It was apparently a fairly serious one judging by this Tweet.
Standard disclaimer: I have zero idea if this is a storyline development or what. I'm not sure how they use the official WWE Twitter feed as it relates to injuries etc. It sounded to me like he left he match with what looked like a legitimate injury though. Will confirm his status and update this article at that time.
DOT NET is reporting that Sin Cara will be out of action for 6-9 months.
F4Wonline/Wrestling Observer is reporting the same.