Real Madrid could suffer their first defeat of the season in that match but I doubt it and I think the worst result for the away team is a draw, not really sure about the score, if it's a draw then 1-1 or 2-2.
Atletico Madrid league form has not been really promising and likewise Real Madrid; their form is good but there are no goal scorers in their squad. i believe its either a 1-1 draw or a Real Madrid 1 nil victory in the Madrid derby