Germany duo Thomas Muller and Manuel Neuer have revealed their frustration following their side's 2-1 defeat to Japan on Wednesday.

Ilkay Gundogan sent Hansi Flick's side ahead in their World Cup opener, but Ritsu Doan levelled in the 75th minute before Takuma Asano netted the winner for Japan eight minutes later.

The defeat has put huge pressure on Germany ahead of their next game in Group E, which is against Spain on Sunday, and La Roja will enter that contest off the back of a 7-0 win over Costa Rica.

Muller has said that his side "played a good game over long stretches", with the Bayern Munich attacker frustrated by what was a "ridiculous" defeat.

"In terms of feeling, we actually played a good game over long stretches," Muller told ARD. "Of course, a good game in football is also characterised by the fact that you convert the chances and superiority into goals.

"The effectiveness at both ends didn't match. It's ridiculous that we are left with a defeat.

"But at the end of the day, when you see what we're leaving behind us and how we conceded the goals at the end, you would say in football jargon that it's not an undeserved loss."

Neuer, meanwhile, has said that his side "gave up the game" on Wednesday.

"I'm totally frustrated and upset that we gave up the game," the Bayern goalkeeper told reporters. "That was more than unnecessary. We created a lot of chances to score, so luck and bad luck go hand in hand.

"The imperative that we wanted to score the second goal was perhaps missing and we brought Japan back into the game.

"After the break, we didn't have that flow of play any more, didn't play with the self-confidence we had in the first half. It was a bit more difficult because they started higher, but we still have to play well."

Germany's legendary former midfielder Bastian Schweinsteiger was also critical of the team's defending during the contest with Japan.

"We made big mistakes again in defence, and as long as we do that we will lose games, it's that simple! Now, please, let's pay attention to the behaviour of Niklas Sule and Leon Goretzka," he told ARD.

"Niklas Sule is a defender. And if someone comes at you in a one-on-one, you don't let them run inside, but close the inside lane and let them run out – less can happen there.

"Sule gives [Kaoru Mitoma] the chance to pull inside and play the pass. Goretzka doesn't get there after that and then stops.

"I don't like that. This is not good. This is very, very bad. Sure, the ball then deflects to Doan, but I didn't like the behaviour before that. That wasn't good enough for a defender like Sule. It's a classic, really serious defensive mistake."

Germany have won the World Cup on four occasions, with their last success coming in 2014, but they were eliminated in the group stage four years ago in Russia.