Barcelona cruised early on in the season, winning with ease both in the Champions League and the Spanish league.
But when it faced its biggest tests yet, having to play against European champion Paris Saint-Germain in the Champions League and old rival Real Madrid in La Liga, the Catalan club faltered.
A 4-2 loss at PSG last Tuesday was followed by a 2-1 home defeat against Madrid on Sunday, when Barcelona looked nothing like the team that had been one of the most dominant clubs in Europe so far.
"In big games, the details are very important, and today they didn't go our way," Barcelona coach Hansi Flick said after the loss to Madrid. "Defeats are part of football. We have to analyze what happened, do things better, and that's what we'll do."
Barcelona had won its first 11 matches to start the season, outscoring opponents 48-11 and finding the net at least three times in 10 games. It held a comfortable lead in the Spanish league and was near the top of the standings of the Champions League.
The loss at PSG, when Barcelona didn't play too badly but couldn't avoid defeat, left the team in eighth place after three rounds in the league phase of the Champions League, the last automatic qualifying spot for the round of 16.
A win on Sunday would have allowed Flick's team to become the first to win its opening 10 La Liga matches. It had already matched Madrid's nine victories from nine games in 1968-69.
But the team struggled on its way to a painful defeat in front of its home crowd. Kylian Mbappé scored twice for Madrid, which moved within three points of Barcelona in the Spanish standings. Atletico Madrid, which beat Deportivo La Coruña 1-0 at home on Saturday, is two points behind Barcelona.
"What matters now is how we react," Flick said. "We have to refocus. Everyone needs to make the right decisions. Rest properly, train well and respond to these defeats."
Barcelona's next matches are against Alaves on Saturday in the Spanish league and Aston Villa next week in the Champions League, both at home.
Flick lamented losing another player due to injury on Sunday, as defender Xavi Espart had to leave against Madrid in the first half. The defense has already been depleted by the absences of Andreas Christensen, Jules Koundé and Eric García. Gerard Martín's blunder in the area led to Madrid's first goal in the clasico.
"The injuries are the biggest concern," Flick said.
Lackluster Yamal
Lamine Yamal was not at his best against Madrid, which saw Kylian Mbappé score twice. Raphinha, Barcelona's scoring leader, got the team's lone goal. Yamal missed a close-range attempt in the first half that could have changed the course of the game.
Barcelona improved in the second half and got the equalizer, but then let the result slip away again after poor defending in a breakaway by Madrid late in the game.
"We didn't play a great match overall. We weren't ourselves in the first half. There were many things we could have done better," Barcelona midfielder Pedri said. "We were very slow and had many silly turnovers, and against these teams you pay the price. We need to improve if we want to keep moving forward."