Rudiger will most likely play in the Barcelona game. He will have to wear a mask from what I read. The injury was bad indeed and required treatment but it won't prevent him to play thankfully.
Rudiger can play but I hope he won't be a starter, Militao-Alaba should be the starter.
Rudiger is better to play in the second half, don't push him too much because he is still injured.
The problem with Real Madrid is that Courtois will not be available due to his back pain.. This will put a lot of charge and pressure on his substitute, hopefully he can stand vs Lewandowski and the others!
I heard a rumor that Courtois will be ready to play against Barcelona in the upcoming El Classico. I think Real Madrid will play with a full team, they must fight all out to return to the 1st place in the La Liga standings.