Indeed Real Madrid opponent is a slightly easier rather than opponent Atletico Madrid, so yes there is a chance for Real Madrid to get points against Atletico Madrid.
I don't think the chance for winning the match will be determined by the previous matches. Although Real Madrid got full points from smaller teams, it doesn't mean Real Madrid always got the points easily. In the last 2 matches, Real Madrid won by only 1 goal difference, it means Real Madrid experienced a difficult match. If they play against Atletico Madrid, it must be harder. I personally can't guess how much the chance of Real Madrid to win against Atletico Madrid.Because yeah there is a possibility Diego Simeone squad is tired, but in the last few matches Atletico Madrid have a good performance. Anyhow, Diego squad looks solid I doubt Real Madrid can win, but be expected Ancelotti can find a suitable tactic in that match at least to surive for draw result.
It is still the early season, how can Atletico Madrid feel tired? 
I think it is a bit nonsense if Atletico Madrid squad will be tired. They are in a good shape, especially after they won 7 goals against Rayo Vallecano.