Atletico may be more favored, but the difference will not be too far. There is even a possibility that Osasuna will give a surprise in the match later. The last meeting between the two was a narrow 1-0 Atletico victory at their home. Osasuna also beat Atletico 1-4. So the match later may be quite tight. Maybe Osasuna also has a chance to win the match. We never know that something surprising sometimes happens on the field.
I have made a promise to myself to stay away from any match that has Atletico in it in the remainder of the league. They are very unpredictable and lose when you don't expect them to.
That being said, another reason why I would be avoiding this game is that Osasuna will be playing at home. Playing at El Sader is difficult for almost everybody. They make it difficult for their opponents, especially the big teams. Barcelona and Real Madrid have both dropped points there this season.
Theres also the fact that Osasuna are chasing a spot in Europe while Atleti donr have much to fight for so Osasuna might be more motivated. I honestly do not know how this game will go so I wont be betting in it.