Jurgen Klopp believes the concussion Loris Karius suffered in the Champions League final is "100 percent the explanation" for his errors in the 3-1 defeat to Real Madrid.
Karius made two mistakes that directly led to Real goals in the final in May after sustaining a blow to the head from Sergio Ramos while defending a corner in the 48th minute, and he was later found to have suffered a concussion as a result of the Ramos incident, with Massachusetts General Hospital saying it "could be possible that such deficits would affect performance."
Speaking about Karius for the first time since the final, Klopp told Liverpool's website that the concussion is not an excuse for the loss in Kiev, more reasoning to explain the German's errors.
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"Whoever had a concussion knows there is not one way how it feels, there are different ways," he said. "He didn't feel it obviously. He had a knock on his head and he felt that but he didn't know he had a concussion. That's how concussions are. The guy who has it is the last one to be aware of it probably.
"With all the intensity of the game, adrenaline and the disappointment after the game, nobody really thought about that. I needed a few days, to be honest, to accept the fact and deal with the situation [of losing the final]. It was not that easy.
"After four days I got a call from Franz Beckenbauer, our Bobby Moore, our biggest football player who is a good friend of mine. He called me and said he came from a doctor, he told me: 'Your goalkeeper had a concussion.'
"I said: 'What?' because in the game, from my position that situation is not very good to see: 'Maybe there was contact or not.' I told him immediately: 'OK.' He said the doctor is the most famous doctor in Germany.
"I said: 'OK, give me a few minutes, I have to fix a few things.' I got all the pictures from different perspectives, saw it and thought: 'How can we all think that the boy who didn't show any weakness in that game until then made these big mistakes in a very important game and nobody thinks it's because of the knock he got?' How can we think that?
"That was, for me, the explanation and I thought: 'OK, come on, we need to check that.' I thought it was too late, you cannot check that. But now I know a concussion isn't coming and going in a day -- if you have one, you see it days later.
"Five days after the final, Loris had 26 of 30 markers for a concussion still. That's clear."
Liverpool were linked with a host of goalkeepers following Karius' performance in the final -- most notably Roma's Alisson, who has been on the Reds' radar in the past.
Karius, 25, returned to Liverpool for preseason training on Monday and is set to feature in the team's first friendly of the summer at Chester FC on Saturday.
"If you ask Loris, he says he didn't think about it and didn't use it for a second as an excuse," Klopp said. "We don't use it as an excuse, we use it as an explanation.
"That's always important, that's what analysis should be: you explain why things happen. So, from this point of view, from my side everything is fine. We don't think about that anymore and we start completely new.
"He was influenced by that knock, that is 100 percent. What the rest of the world is making of it, I don't care. It's really not important what the people say. We do not use it as an excuse.
"Now people could think for us it is the explanation -- and for me it is 100 percent the explanation and that's all."
Meanwhile, new signings Naby Keita and Fabinho are likely to make their first appearances for Liverpool at Chester on the weekend.
"We don't want to waste time," Klopp said. "They are in, it's good. It's our first preseason game so let's start.
"If they'll start, I don't know, to be honest. I haven't made the lineup so far, I have to see who is available. But, yes, they will be involved for sure."
Georginio Wijnaldum and Virgil van Dijk will not feature at Chester, but are set to return to Melwood the following day for testing after being granted extra time off for featuring in friendlies for the Netherlands this summer.