Carlo Ancelotti says Bayern Munich were surprised by Hoffenheim as the third-placed Bundesliga side scored their first-ever victory over the defending champs on Tuesday.
Andrej Kramaric's 21st-minute goal sealed a win which moved the hosts to within one point of second-placed RB Leipzig and extended their unbeaten run to seven games.
And Ancelotti admitted his defence had difficulty dealing with Hoffenheim as they dominated the opening 45 minutes.
"Congratulations to Hoffenheim. We were a bit surprised by their play and weren't well organised in defence," Ancelotti told the Bayern website.
"It was a very intense match. Our first half wasn't so good. We did a much better job in the second half, we were more aggressive then. We had our chances to level the scores.
"But things just don't work out on certain days, that's football."
The goal was the first Bayern have conceded in their last six Bundesliga matches, and winger Arjen Robben backed his manager's sentiments after the match.
"It's a pity, we mustn't allow that to happen. The first half was unnecessary. We lacked discipline, we were always a step too late, which is why we had problems," Robben said.
"The second half was much better, just as it should be. We were dominant and had our chances, but a goal refused to come today."