Barcelona manager Xavi urged his side to take a long look at themselves and work out how they could lose 1-0 to relegation candidates Cadiz at home on Monday.
The Blaugrana dominated possession and were far superior on the stats sheet, but they could not find a way through the stubborn Cadiz defence and ended up losing to a goal from one-time target Lucas Perez shortly after half-time.
The result leaves Barcelona second in La Liga but level on points with Sevilla and Atletico Madrid below them, although Xavi's men still have one game in hand over their rivals.
After the game, Xavi admitted losing against Cadiz was a huge blow to his side's top four aspirations and questioned how a team with Barcelona's quality could fail to win a game like this.
"I'm angry," he began. "We have missed a very good opportunity, a golden one, to move ahead of the other Champions League hopefuls and we've pretty much said goodbye to winning La Liga. I am angry.
"We have to play with more determination. We have to do more. I am the most responsible, but I am angry because we're playing for qualification for the Champions League here. We should have shown more enthusiasm.
"We're improving, but we want to do more, be fighting for titles. We all have to improve. We have to look each other in the eyes and ask where the desire was. A team such as our cannot be losing to Cadiz. At home, we have to show more desire and character.
"Everything worries me. We have to stay humble, we haven't achieved anything yet. There has been a change in the model, but we have to improve. We have to play with more impetus. We have to score chances, and it's essential to get ahead on the scoresheet. We have to improve."
The defeat was Xavi's first in La Liga since December last year, but came just days after they lost at home to Eintracht Frankfurt in the Europa League quarter-finals
"We had a good run, but in the last two or three games, we haven't been ourselves," Xavi said. "We have to show more personality, win more duels... we just have to be better.
"There are seven finals left. We have to be self-critical and own our mistakes to improve from them."