Probably nobody was expecting such a comeback by Espanyol.

How did Atletico Madrid managed to lose like that?
Atletico's coach is the only one who could answer that question correctly. He changed strategy when his team dominated the game, owned most of possession, also gave so much pressure to the Espanyol. One of the stupidest decision i have ever seen from a manager at his calibre. No doubt his team is always stagnant and never progressed well.