Bayern Munich goalkeeper Manuel Neuer admitted his rare error cost the Bundesliga league leaders in a disappointing 1-1 home draw against his former side Schalke.
Robert Lewandowski fired the German champions into a ninth minute lead, but Naldo equalised from a free kick only four minutes later, capitalising on a rare mistake from the ex-Schalke man in the Bayern goal.
The Brazilian defender's fierce shot squirmed agonisingly through Neuer's grasp, and the keeper told Sky Sports Deutschland: "It has nothing to do with the wall. It's clearly my problem.
"But I was totally convinced that the ball would skip higher. If we had bumpy turf here, then it definitely would have."
Bayern were below-par for long periods against a resolute Schalke side. Javi Martinez could have won the game with five minutes remaining, but Bayern's record signing fired narrowly wide when placed inside the box.
Neuer added: "Of course it's always about the result, but it's also about the way you played too. We didn't play as we had intended, especially in the first half. That's the overriding feeling at the end of the game.
"In the second half we tried everything and maybe we were a little unlucky with our chances to not make it 2-1 at the end. But you can't always have as much luck as we had recently against Freiburg and Bremen."
Bayern boss Carlo Ancelotti paid tribute to the visitors for their performance at his postmatch news conference.
"It was a tough game for us, Schalke played well,'' Ancelotti said. "We started well, but then we were not compact enough, the defence and midfield lines were not close enough together. We did not win the important balls, so we had problems. Overall, it was not enough, now we are focusing on the next game."
Analysing his side's disjointed performance, the Italian added: "It's not a problem of quality, but of sacrifice."
After relinquishing Bundesliga points at home for the third time this season, Bayern moved four points clear of Leipzig who play Borussia Dortmund later on Saturday.
Schalke coach Markus Weinzierl felt his side did well to fend off the expected second-half onslaught from Bayern.
"We delivered a good game, especially in the first half,'' he said. "We did well under the early pressure and then later we failed to take advantage of the chance we created where we needed to be in the lead, we did not do that and so were again under pressure in the second half.
"It is also clear you need some luck against the individual class of Bayern, and we had that."