Barca ground out a 1-0 result at the Nou Camp after Zlatan Ibrahimovic smashed home a contentious penalty six minutes before the break.

With Lionel Messi missing through injury, Barca looked tired and lacklustre in what was already their 26th match of a hectic season.

"We have made a large sustained effort (this season) and in the second half, that showed," Guardiola said.

"They pressed and it was hard for us. We have to give this win an extra value, because it was a derby match and because the players have accumulated a lot of tiredness and debilitation in the last few weeks.

"I congratulate the players, because they have beaten a great rival and I believe this encounter is a good test for what is to come," he said, referring to Barca's forthcoming trip to Dubai for the FIFA Club World Cup.

The Catalans face Mexican side Atlante in the semi-finals on Wednesday, but must first tackle a long journey to the United Arab Emirates before that.

"We leave at 11 tomorrow and arrive at 23:30 their time.

"Spending so much time on the plane two days before the semi-finals of the World Club Championship against a rival that is already there will not benefit us," he said.

The Barca coach also revealed the travelling party faces a two-hour stop in Turkey on the way to their final destination.

Meanwhile, Espanyol coach Mauricio Pochettino was happy with his side's performance, if not the penalty decision.

"In the second half we were more daring and there was no difference between Barca, who are champions of everything, and Espanyol," he said.

Following what was the club's fifth straight defeat, the Argentinian now hopes his side can produce that kind of performance more often.

"We need to maintain that kind if intensity in all of our games," he said.

Regarding the penalty decision, Pochettino backed the explanation given to him by Raul Baena, who was penalised for hauling down Xavi with the latter apparently exaggerating the contact.

"I can only go by what my player says and he told me it wasn't a penalty," he said.

Guardiola, though, claimed Baena had admitted it was a spot-kick.

"Baena recognised to Xavi that it was a penalty," he said.

Nevertheless, the Barca coach is sure the press will have plenty to say on the matter.

"I can imagine what will happen. We have been used to it for the last year," he said.