Barcelona coach Luis Enrique made no excuses after they lost 4-3 at Celta Vigo and missed the chance to top La Liga on Sunday.
The champions were without injured talisman Lionel Messi and Luis Enrique left captain Andres Iniesta and experienced centre back Javier Mascherano out of his starting lineup.
His decisions soon backfired as Barca were blitzed by an intense Celta side, who raced into a 3-0 halftime lead.
"I cannot be satisfied, we've wasted the chance to go top before the international break," Luis Enrique said with his stuttering side two points off the pace in fourth behind leaders Atletico and Real Madrid and a point behind Sevilla.
"We weren't at the right level apart from in the first 15 minutes. We kept on losing battles and they anticipated our mistakes. We did not cause them any problems. When you go 3-0 down to Celta at halftime you can have no excuses."
The coach said he took full responsibility for the chaotic display but said he had no regrets about his team selection.
"I have nothing to regret. The most disappointed person after a defeat like this is me but it's my job to take decisions," he added at the news conference.
Barca reasserted themselves in the second half when a header from Gerard Pique and Neymar penalty reduced the deficit to one goal before they were floored again by a catastrophic mistake by keeper Marc Andre ter Stegen.
The German international was caught in possession in his own six yard box and made an attempted clearance which cannoned off Celta midfielder Pablo Hernandez and bounced straight into the Barca net.
Luis Enrique, however, offered Ter Stegen his support.
"The Barcelona goalkeeper should always take risks but today is not the game to criticise individuals. Ter Stegen gives us a lot and we're not going to kill him for this," he said
Barca defender Pique, who scored twice in the second half, said they should take heart their reaction after the break.
"We played better in the second half and had nothing to lose. It almost paid off. We can learn from this," Pique told Movistar plus.
"The game looked over and all we can take from this is the reaction of the team and the pride we showed but there are many things we need to improve. There's a lot of the season left to go and it's still very tight."
(Reporting by Richard Martin; Editing by Ken Ferris)