Hansi Flick blamed Bayern Munich's lack of clinical finishing for a 2-1 loss at Borussia Monchengladbach that left the Bundesliga champions seven points adrift of the summit.
Bayern seemed to be bouncing back strongly from their home defeat to Bayer Leverkusen last time out, enjoying a dominant first half, with Ivan Perisic firing in the opener shortly after the restart.
But they failed to get a crucial second and Gladbach, who only had one shot in the first 45 minutes, equalised when Ramy Bensebaini headed home Jonas Hofmann's corner.
Bayern's inability to kill the game came back to haunt them at the death as substitute defender Javi Martinez needlessly brought down Marcus Thuram in the box.
Martinez was shown a second yellow card and Bensebaini tucked home the penalty to keep Gladbach top of the table.
"It is important that we play football well, on the one hand," interim head coach Flick said. "We did that in the first half and created a lot of chances.
"Of course it is annoying that we do not make the most of the possibilities, so we leave Gladbach in the game.
"This is a situation we would normally have had to close earlier. Just as it was against Leverkusen last week. The team has the quality to score goals.
"Unfortunately, we do not do it at the moment. In the end, it's just that the football is settled with goals."
Flick added that Jerome Boateng had to be replaced by Martinez having struggled through the game due to an injury problem.
Flick's opposite number Marco Rose has had a remarkable impact since taking charge of the Foals but he accepted Gladbach had to ride their luck to close out a sixth straight league win at home.
"We saw two different halves. In the first half we barely had possession," he said.
"There is always a difference between what you do against Bayern and how you implement it on the pitch.
"We continued to play for victory and that rewarded us with the penalty goal. In the end, it is certainly a lucky victory, but it helps us a lot in the development."