I personally feel that Madrid will still not underestimate Sevilla in this match. Even though Sevilla's condition is quite bad, that doesn't mean Ancelotti will be careless in implementing the formation. 3 points can be achieved, but Sevilla will play at home which is a plus point and try to improve its poor performance.
Playing at home will not guarantee that Sevilla can beat Real Madrid and maybe Sevilla must be prepared to accept the fact that Real Madrid has been impressive so far. In terms of squad depth, it is clear that there is a huge difference and Real Madrid seems to have no gaps that could allow them to lose.
Maybe Sevilla can beat Real Madrid if they succeed in pressing and continuously attacking. But attacking continuously is not a good option and Real Madrid with its counter attack could destroy Sevilla within 90 minutes. The safe bet is of course on Real Madrid and I would bet on Real Madrid without the slightest doubt.
I do believe that Real will have some hard time not because they will play badly but because the yare not going to be ready to play at 100% right away. They still do not have a proper striker and we have seen how troublesome that could be. Hell Jude had to score a bunch of goals because there were no strikers where striker should be, and it's mocked that he scores easy goals like tapping the ball in and nothing more, but that positioning is the most important thing for a striker not a midfielder and he is doing something amazing.
If a midfielder is at a place where all he has to do is touch the ball and he scores, isn't that also amazing? I mean if it was just a few ones then I would understand but he scored as much as Ronaldo scored in his early games, that means he is doing something right and we should not be judging his goals. I believe they need a striker that can do that and lift some pressure above from Jude and try to score himself, that would be a lot more help.