Hansi Flick did not offer any excuses after Barcelona's poor performance in their shock 1-0 defeat away to Real Sociedad on Sunday evening. (More Football News)
Sheraldo Becker scored the only goal for the hosts in the first half, with Barca offering little while searching for a comeback.
The defeat ended Barcelona's run of seven straight victories in all competitions, although they remain six points ahead of Real Madrid – who have a game in hand – at the top of LaLiga.
"Today was not our day," Flick told a press conference.
"I think we have to accept this result because they played decisively. It's clear, there are no excuses. We didn't create enough chances.
"We started well with the ball, I was happy, but then we started to suffer and their goal came. We also made some bad decisions and that's something we have to live with."
Barcelona had scored in every game they had played in all competitions this season until Sunday, although they did not even manage a shot on target at the Reale Arena.
It is just the second time they have failed to do so since at least the 2003-04 season, after a match against Malaga in September 2014.
Real Sociedad arguably could have won by a wider margin after creating 14 chances and generating 1.85 expected goals (xG). The Barcelona defence made plenty of errors, which was something that concerned Flick.
"The responsibility for the defeat is ours. We could and should have played much better," Flick said.
"We haven't held possession of the ball the way we wanted and suffered. But the games we have played before have been fantastic, and I appreciate what the team has done so far this season.
"We tried until the last second, united, and I told the team that. But today we weren't strong enough to deserve a better result."
