Jürgen Klopp said his first defeat as Germany boss -- a shock 1-0 home loss to Greece in the Nations League on Sunday -- was "part of the process" as he looks to rejuvenate the four-time World Cup winners.
Greece substitute Dimitrios Kourbelis scored with a deflected shot in the 74th minute, somewhat spoiling the mood in Augsburg where Klopp was making his home debut as Germany coach.
It was Germany's first ever loss to Greece, the 2004 European champions.
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"It's part of the process, absolutely," Klopp told broadcaster ARD. "The lineup, the formation, the many changes -- that is all 100% down to me."
Klopp oversaw a 1-1 draw against the Netherlands in his first game in charge on Thursday.
He made five changes to his starting lineup on Sunday. His new-look team dominated the first half against Greece with 77% possession according to Opta, albeit without creating many clear goal-chances.
Karim Adeyemi forced a fine save from Konstantinos Tzolakis in the 32nd minute but the Greek goalkeeper otherwise had little to do.
"Football, that's how it is," Klopp told UEFA.com. "Drawing this game tonight, I could have easily taken it, but losing -- that's harsh. I don't think we deserved that, but it happened anyway, and here we are.
"Greece had a plan for the game tonight. We have to be more convinced about what we are doing. And in that moment, things will be good."
The visitors became more ambitious in the second half with Fotis Ioannidis missing a big chance, and defender Jonathan Tah preventing another, before Kourbelis stunned the home fans.
"To be honest, we simply didn't perform well enough," Tah said. "Of course we're disappointed and angry when we lose a match. But the important thing is that we stick together.
"That won't change, the euphoria around the new coach. If we don't play well and we lose, obviously not everyone is going to be happy. But we can make up for it in the next game."
Germany next face Serbia in Munich on Thursday before traveling to face Greece in the reverse fixture next Sunday.
Klopp said he would continue to rotate his squad.
"We'll change the squad, change the team," he said. "The good thing is that the other team doesn't necessarily know how we're going to play, but we don't know right now how we're going to play, because we have to bring that group together again.
"We can take a lot out of this game, and we will do that -- and we'll work on it."
The Associated Press contributed to this report.