Real Madrid midfielder Sami Khedira says Manchester City are among the best teams in the world.
Los Blancos currently sit second in Group D with seven points from four games, while City are bottom of the group after picking up just two points.
"City have fantastic players and they are all capable of being match-winners. It doesn't matter who plays. We'll need to be very focused to try and contain them. They're among the best in the world," Khedira was quoted as saying on the Bwin website.
"Dortmund showed us that it's possible to challenge City in Manchester, playing a compact game, fighting for every ball and trying to play your natural game.
"We shouldn't allow ourselves to be influenced by our opponent, we need to dominate the game with our attacking potential."
Madrid recorded a 3-2 win over City at the Santiago Bernabeu earlier this campaign.