Diego Simeone was impressed with Espanyol's "almost perfect" defending as Atletico Madrid were held to a 0-0 draw at Vicente Calderon on Saturday.
Atletico were looking to take full advantage of the top three in La Liga all dropping points, as third-place Sevilla lost at Granada, while Real Madrid and Barcelona played out a 1-1 draw in El Clasico.
But Simeone's men struggled against a defensively shrewd Espanyol side, as Quique Sanchez Flores returned to the Calderon and saw his team pick up a fifth successive clean sheet in La Liga, meaning Diego Lopez has now gone 496 minutes without conceding.