Angel Di Maria believes Real Madrid are playing much better now than when they were when Borussia Dortmund had the upper hand during their Champions League group meetings in the autumn.
Dortmund beat Madrid 2-1 at the Westfalenstadion in October, while Mesut Ozil's 89th minute free-kick rescued a 2-2 draw for Jose Mourinho's men at the Bernabeu a fortnight later.
Those games came at a time when Los Blancos were struggling for form and consistency amid injuries and internal squad issues.
Speaking ahead of Wednesday's semi-final first leg in Dortmund, Argentine winger Di Maria told Madrid's official website Madrid were now much stronger and more confident.
"When we played the first couple of matches, we were not as good as we are now," he said. "Things are going much better, the defence is more compact. We have the extra confidence now to do very well in the tie."
Jurgen Klopp's side played a clever counter-attacking game in the two group encounters, something Di Maria said had reminded him of Madrid's own preferred style of play.
"We know they can score goals on the break, as we suffered from that already," he explained. "They are a very similar team to us, with a very strong counter-attack, and they are also on a good run of form.
"I believe that it will be the same this time. We will have to be at 100% to get through. These are two great teams. It will be a very difficult game and a great spectacle for the fans. It is very difficult to say who will go through."
German internationals Sami Khedira and Ozil would have important roles to play, Di Maria said.
"Khedira and Ozil have improved tremendously and have developed in every way," he added. "They are both playing as well as ever. Sami is doing really well, and the coach really sees that. Mesut is also getting a lot of assists. Both players are important for us."