Boss Marcelino wants his Valencia side to be at their very best against Celtic at the Mestalla on Thursday night.
The Spanish club are 2-0 up following an impressively comfortable first leg in Glasgow and odds-on to reach the last-16.
Marcelino, speaking through an interpreter at the club's training ground, stressed how keen he was to have his players focused on another good performance.
He said: "Being relaxed is not good, ever.
"The team's mind-set should be to win, no matter what happened in the previous match.
"We are going to try any way we can to convince the players that maximum effort, maximum concentration is the way to achieve a good result which is to be in the next round.
"All matches are important. We cannot relax or think that everything is already done. We want to win again.
"Celtic have a clear way to play, a clear philosophy, if they could not do it more effectively it was because of the good job from an organisation and commitment point of view from us.
"Also, we scored at important times in the game.
"Before the first game we felt the first game would be dangerous and difficult but if it was not it was because of the wonderful job of our players. We don't believe they will change hugely.
"It is not decided. We have to have the utmost respect for Celtic.
"We don't want any surprises and the best way to avoid surprises is to think of ourselves and try to get close to our best performance and respect fully the opponents' ability."
