Mergim Berisha’s goal just before the hour mark condemned Bayern to their first defeat of the season at the Augsburg Arena.
It also made it four Bundesliga games without a win for the reigning champions, the longest winless run in the league since the 2001-02 season.
Speaking at a press conference alongside Augsburg boss Enrico Maassen after the game, Nagelsmann praised the winners but believed his side should have won the game.
“Congratulations to Augsburg and Enrico for their victory against us,” he said. “When I look at the stats, I think we should win this game if we defend that free kick properly [that led to the goal].
“It was hard to break them down after it went 1-0.”
Bayern had 19 shots against the hosts’ 11, but Augsburg edged that out in terms of expected goals, 1.56 to 1.52, according to Opta.
Few of the visitors’ players shone and it was another struggle for Sadio Mane, who had just one shot on target, even less than Bayern keeper Manuel Neuer (two), who scored at the end of set pieces.
“I’m not going to talk about individual players here, I’m going to talk to them directly,” Nagelsmann said. “There’s always a difference between what I say to you and what I say to the team.”
Augsburg ended Bayern’s record 87-game streak in the Bundesliga with at least one goal, having done the same in 2014 when they ended their Bavarian neighbour’s previous record 65-game scoring streak.
That naturally led to questions about former striker Robert Lewandowski, who scored twice in Barcelona’s 3-0 win over Elche in La Liga at the same time as Bayern lost at Augsburg.
When asked about the lack of a number nine, Nagelsman quipped, “What are you going to do if I say yes or if I say no? We have a classic nine with [Eric Maxim] Chupo [Moting] and we signed it today.
“It doesn’t matter what I say now. If I say no, you’ll say I don’t see a problem, if I say yes, you’ll say we’re missing Lewandowski.”
At the end of the press conference, Nagelsman added: “I think about everything. About the situation, about myself, about everything.”
His number two was grateful for the kind words, and Maassen explained that his team won by taking risks.
Despite Bayern having 10 shots compared to the home team’s two in the second half, Augsburg matched their efforts in the opening 45 minutes with both scoring nine shots apiece.
“Thank you Julian [for his congratulations]”, said Maassen. “I’m very happy with the way my team played.
“We were ready to take risks, I told the team that we can defend and maybe lose 1-0 or 2-0 or we can play high risk. We may concede more goals, but we will also have a chance to win and you have to attack if you want to try to beat them, so we chased a lot of balls.
“We missed a lot of chances, but [goalkeeper Rafal] Hikievich was extraordinary.”