The tie marks Lopetegui's first game in charge since his appointment.
He said: “I think they are working very hard, focused, concentrating, trying to understand what we want to do. In the matches against Birmingham and in Spain against Empoli and Cadiz, step by step I think they are understanding more about us, and in the same way us about them.
"We have to improve more in the next matches and tomorrow is the first important test because it's the first official match.
“We are playing an exciting Carabao Cup tie, we want to win, we know it's going to be a hard task because it's the cup and we are talking about only one match. This is football and we know what can happen, so we have to be ready, but at the same time, we want to win this match a lot."