Atletico Madrid defender Diego Godin has said his team must regain their defensive discipline after the weekend's 3-0 home defeat to city rivals Real.
After conceding just three goals in their first 11 games in all competitions, Atletico have now let in nine in their last five outings.
And speaking ahead of Wednesday's Champions League game at home to PSV Eindhoven, Uruguay international Godin told a news conference: "One of our strengths has been solid defence.
"We will try and build a victory from that solidity, which has been a key factor for the team in recent years.
"We have lost goals and points down to details. We must correct them. They are not just small details, as they have cost us games."
Some Atletico fans have voiced concerns that coach Diego Simeone's move towards a more possession-based style has left his team open at the back.
But Godin said: "It has been a continuous upward curve, improving our play, each season.
When you lose it seems all is bad -- but it is not like that. We are very good, and we know our path very clearly.
"We know what the coach wants, and we are with him to the death on that. That is the most important thing."
He said the players were confident and added: "These are moments that can happen, you can lose a game. But we are just thinking about PSV, our next objective.
"You must be balanced, relaxed, and inside our message is to be confident. This is the same team as a month ago, a good team. We know our strengths and that we can improve."
Godin said a home victory over PSV, which could seal top spot in Group D if Bayern Munich do not beat Rostov, would lift the mood around the Calderon.
"The Champions League is a great objective for us -- just like La Liga and the Copa," the former Villarreal defender added.
"We know the special relationship we have with the Champions League. Tomorrow is an important step to keep moving towards that."