Barcelona coach Luis Enrique said his side needed to keep their heads better after Saturday's 1-0 La Liga defeat at Real Sociedad.
Barca's poor run at Anoeta continued as Mikel Oyarzabal scored the only goal with a fine header on just five minutes and -- despite dominating possession for the remainder of the game -- Lionel Messi and company were unable to find a way past home keeper Gero Rulli.
Following the draw at Villarreal and Clasico defeat at home to Real Madrid, Barca have now taken just one point from the last nine available as a La Liga race previously thought all but over has opened up dramatically.
The Blaugrana coach told his postmatch news conference that his team had paid for a poor start and then not shown the composure needed to turn the game around.
"The game began in the worst way possible," Luis Enrique said. "We played a bad first half. We wanted to turn it around with more heart than head and we needed more control. I liked the second half more.
"Rulli, as usual against us, played a great game. We did not deserve to lose."
The former Barca midfielder called on his team to bounce back quickly and positively from this setback ahead of Wednesday's Champions League quarterfinal second leg at Atletico Madrid, where his side hold a 2-1 advantage after their first game.
"These type of games can weigh on you like a stone," he said. "But all is still to play for. I want to see how we can improve; not to leave here crying but to come out of thinking about what each one can do for the team. The objective is to win [at the Calderon], but it will be difficult."
Barcelona's lead in La Liga is now three points above second-placed Atletico Madrid, with third-placed Real Madrid a further point back with six games remaining.
Luis Enrique said his team were still better placed to take the title than they had been at this stage last season.
"But we are still leaders, with a four-point advantage," he said. "To speak negatively does not help the team. Now we must lift ourselves up and leave this nice stadium which is not a good place for us.
"Last year at this stage we just had a two-point advantage, without the goal average. This is a marvellous chance to show we are the best team in the world, as it says on our shirt."
Barca must improve their La Liga performances quickly, Luis Enrique accepted, ahead of next Sunday's home game against relegation-threatened Valencia.
"There is a title race, of course," he said. "The others are pushing, and we have not been at our level in some games. We cannot commit any more mistakes.
"The team which does best in the last games will win this league. I want to see the Camp Nou as full as ever next week against Valencia."