The Yellow Submarine have won their previous two LaLiga games.
Emery said: "The idea is, given the importance of the match, to count on the best players. From Tuesday until Sunday there are days to recover. Tomorrow we'll see how they are. Tuesday's match will be a mental and energetic strain and a physical demand, but the players are used to playing matches with high demands. We'll have to see how the players are recovering after that match. Espanyol are warning us of a difficult game and we have to face it in the best possible way.
"We are doing relatively well. When you consider LaLiga in 38 games, we're better than we were two months ago, but we're coming off the back of a poor first half of the season. We need to be in the European places. We are not favourites, but we are aspiring to be in the Champions League places. We have to be able to achieve more between now and the end of the season by finding credibility and consistency in LaLiga. We are optimistic, but, at the same time, cautious.
"To be in Europe next season we have to keep winning. Our challenge is to always win again and again. If we set the bar high, it is normal that we will always have more chances to succeed, also taking into account the opponents and the difficulty of the game. I want to maintain the highest level and focus in every game."