Germany coach Joachim Low has said "far-reaching measures and clear changes are needed" after the World Cup holders' shock group stage exit.
Low's side finished bottom of their group after a 2-0 loss to South Korea and, although Low signed a contract until 2022 before the tournament, Germany's earliest exit since 1938 has sparked speculation that he could step down.
"After the pain and huge disappointment of our exit, we need a bit of time to somehow digest it and consider the consequences," Low told reporters at Frankfurt airport on Thursday. "We have to admit that we really disappointed at this tournament.
"We are truly sad that we could not deliver to our fans what they expected. The team didn't show what it is normally capable of and, as the coach, I am responsible for this. I have to ask myself why we didn't manage this.
"There isn't a single reason -- there are numerous reasons for our exit. The fact is that we weren't in the form that we showed in previous years. We have to analyse what mistakes we have made. I think we need to take action.
"Far-reaching measures and clear changes are needed, and we must talk about how we do that."
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Low said Germany had been in a similar position when he arrived as assistant to Jurgen Klinsmann in 2004 after the resignation of Rudi Voller following a group stage exit from the European Championship.
"After that, a lot of changes were made," he said. "We made our way to the top over a period of 14 years -- we were the most consistent team in the world for the past 10 years and became world champions."
Midfielder Sami Khedira backed Low, adding that he would consider his own international future in the weeks ahead.
"He can and should definitely stay on -- but whether he will is his decision," Khedira told Bild. "I want Jogi to continue. He has done an excellent job over many years, integrating many young players into the team."
Jurgen Klopp, Jupp Heynckes, Thomas Tuchel, Miroslav Klose, Marcus Sorg, Thomas Schneider, Stefan Kuntz, Matthias Sammer and Klinsmann were mentioned by Bild as possible candidates should Low step down.
Tough moment. Feeling with all our fans who supported us. We were not good enough this year... pic.twitter.com/vkUpkHc18c
— Toni Kroos (@ToniKroos) June 28, 2018
Meanwhile, Toni Kroos gave a damning assessment of Germany's failure.
"I don't know if this is the darkest moment for German football, but it is definitely a very black one," Kroos said. "I don't think any of us expected this at all.
"In the end we did not do enough. To be honest, if we can't score a goal in 90 minutes against South Korea then we don't deserve to go through. We got what we deserved. We were not unlucky."