Lionel Messi has admitted that Barcelona's 3-2 defeat to Valencia was a "bad day" for the club.
The Catalans have consistently held the top spot in Spain since the start of the season, but their loss at Camp Nou to los Che has given Atletico Madrid and Real Madrid a chance to leapfrog them on Sunday.
The Argentine attacker was understandably disappointed with the result but says he is pleased to be back in action for Barca after spending around six weeks sidelined with a hamstring injury before the winter break.
"It was a bad day," Messi admitted on Sunday at an advertising event, referring to their first home defeat in La Liga of the season.
"I'm happy because I've played several games in a row. Mentally, I am in very good place. It is true that some things went wrong for me fitness-wise but now everything is forgotten."
Messi will hope to guide Argentina to World Cup glory this summer in Brazil, though he accepts that the path to the final will not be without its problems.
"Winning a World Cup is a dream of an entire country," the 26-year-old added. "Our team has grown and, although we have to iron out some issues, I think it would be very possible to play in that final."