Partial Source: Pwinsider
There is a banner ad on the front page of WWE.com advertising a 2 out of 3 Falls Match between Rey Mysterio and Alberto Del Rio for Sunday's Survivor Series pay-per-view event. This appears to be an error as no such match has been announced. A bout pitting Team Mysterio against Team Del Rio in a Traditional Survivor Series Elimination Tag Team Match is still advertised for the event on WWE.com.
UPDATE: Word is that the traditional Survivor Series elimination tag match was a last minute addition to the PPV. The original plan was to have Rey Mysterio vs. Alberto Del Rio in a Best of Three Falls "Lucha" match. The match was expanded because Mysterio is working through an inner ear infection. That's why he was used so little on TV this week. A scheduled match between him and Del Rio on SmackDown! was turned into a Battle Royal for the same reason.