Barcelona's Javier Mascherano has praised the impact of Javier Aguirre on Espanyol ahead of the Catalan derby on Sunday.
Barca sit on top of La Liga and head into the home tie with spirits undoubtedly high after a flawless December, though midfielder Mascherano warned his team-mates not to underestimate their hosts.
"On Sunday it will be a difficult game," the former Liverpool man told Barca TV.
"They are a very difficult opponent. Aguirre has changed the dynamics of Espanyol (and) the picture is very different to what it was with the previous coach (Mauricio Pochettino)."
Mascherano also revealed his relief at Tito Vilanova being back among the players - the head coach was absent from matches during the final month of 2012 after a cancer relapse which required surgery.
"For us, after how we felt before the match against Real Valladolid, it is very important to be close again to Tito," he said.
"It is great news for our group."