Actually I seriously doubt Tobi is going to save Sasuke. I mean, he does have alot of confidence in Sasuke's abilities.
At this point, I doubt Sasuke will win with Tsukuyomi, not because I think Raikage will beat it, but because it would be really stupid to win with a Tsukuyomi now. I mean Sasuke went so far as to use Amaterasu 2x and Susanoo, so to win with Tsukuyomi would be ridiculious since he could have done that at start of battle and save some chakra as well as the bleeding from his eyes. I am thinking since Raikage sacrificed his left arm to hit Sasuke, perhaps the black flames will spread over his body and then he will die. >.>