The veteran defender remains a free agent after leaving Sevilla over the summer - and has now been linked with a return.
But Pimienta says: "I have used the five centre backs because I have confidence in all of them. When I make the lineup I do it convinced that it is the best for that game, knowing that there are others prepared. I am clear about the centre-backs who will play tomorrow, but anything can happen. People must be alert. Marcao came out the other day at a difficult time and had a good game.
"He (Ramos) is the history of football, of Real Madrid, the National Team and Sevilla. But Sergio already said goodbye. I have some players and I can't talk about the rest.”
On Sevilla's late market plans, he also stated: “If no player leaves it is difficult for another to come. If they come, they must improve what we have. The sports management is very attentive.
"Any wishes? I would like a player who scores a lot of goals, of course, and maybe we have fewer numbers in the midfield. But I'm happy with how the squad is. I don't fear there will be any unexpected departures but it wouldn't surprise me.
"Sevilla has high-level players, there are emergencies and teams with negative results. We have the obligation that if they come for an important footballer, the sports management resolves it.”