Ronald Koeman feels the poor attitude of Barcelona’s players had a role in their shock 2-1 defeat at the hands of promoted Cadiz in La Liga.
Lionel Messi was the best player on the pitch with a 9.0 FC Rating but even he could not prevent a damaging loss, already their fourth in the top flight this season.
Barca now have just 14 points after 10 games, with the Cadiz loss sealing their worst La Liga start for 32 years.
They are already 12 points behind league leaders Atletico Madrid and Koeman concedes a title challenge looks increasingly difficult.
"It's a giant step backwards in our chances of fighting for La Liga," Koeman said after the match.
"It's disappointing, but we have to accept it. A gap of 12 points to a team as strong as Atletico Madrid is a lot.
"There are still a lot of games to play but if we don't improve our attitude and our ups and downs away from home, we can't say any more."
The manner of the goals Barca conceded frustrated under-pressure Koeman, with the second one seeing Clement Lenglet fail to control a simple throw-in, allowing Alvaro Negredo to charge down Marc-Andre ter Stegen and score the winner.
"The defeat is difficult to explain," added Koeman.
"We've come here after some good games, but the first half wasn't good.
"We were better in the second half, but the way in which we lost was incredible. We lost due to an unexpected mistake that you cannot make.
"It came from not being focused. The attitude wasn't good and not just from the defenders.
"It's very hard to explain some of the goals that we've conceded. I think it might be because of a lack of concentration.
"We lack aggression without the ball and that might be why we concede.
"It's not easy to explain that second goal. We conceded goals that I couldn't have imagined."