Barcelona coach Pep Guardiola admits his side produced an off-colour display in their shock 2-0 home defeat to Hercules.
The newly-promoted Primera Liga outfit caused a major upset at Camp Nou on Saturday as Paraguay forward Nelson Haedo Valdez notched a brace on his debut.
Guardiola was full of praise for the La Liga new-boys, but lamented his side's below-par performance.
"I congratulate Hercules," said Guardiola. "They came here and played well. They made it difficult for us and they got their reward."
He added: "We lacked our usual fluidity. There are so many details we can improve on. We'll have a look at it and try to overcome it.
"We have overcome so many things since I've been here and we will again."
Guardiola chose to rest several of his first-choice players on Saturday with one eye on Tuesday's UEFA Champions League clash against Panathinaikos, but the Barca coach insists he fielded a side good enough to win.
"I picked a team to win the game," he said. "These are all Barca players and they are all top-level footballers.
"It was a good enough team, but we lacked fluidity."
Former Liverpool man Javier Mascherano, who joined Barca in the summer, was replaced at half-time by Xavi as Guardiola looked to adopt more of an attacking approach in the second period.
But the coach insists he was pleased with his new signing's debut, adding: "Mascherano played really well - I just felt we needed to change things."
A number of Guardiola's players entered the Hercules clash on the back of an international friendly in Buenos Aires, where Spain lost 4-1 to Argentina on Tuesday evening.
But while acknowledging that match was not ideal preparation, Guardiola refused to make excuses for the defeat.
"Ideally you would want the players to travel in Europe, not to South America and other places, but these things are beyond our control," he said.
"I don't know if it was a question of tiredness. There was no talk of physical problems when we beat Racing Santander 3-0 or when we beat Sevilla 4-0 in the Supercopa.
"We still created enough chances to win the game. Today we didn't take our chances, but we had a lot of opportunities."
The coach is staying calm ahead of Tuesday's European clash, adding: "It's another big match and we'll have to pick ourselves up like we have done before - there is no need for alarm."
Mascherano, meanwhile, was disappointed to lose his first game in a Barca shirt. He said: "It was a great surprise to start the match and my team-mates helped me a lot.
"I felt comfortable, but it's a bitter feeling to lose. There's not much more I can say - Hercules played a virtually perfect game."