Jurgen Klopp has claimed that Loris Karius was "100 per cent" affected by concussion in Liverpool's Champions League final defeat by Real Madrid.
The goalkeeper made two costly mistakes, gifting Karim Benzema the opener before allowing Gareth Bale's late strike to slip through his hands as the Reds lost 3-1 in Kiev.
Karius collided with Sergio Ramos during a Real Madrid corner moments before Benzema's goal, and tests at a Boston hospital days after the final confirmed the German had suffered concussion.
The 25-year-old returned to pre-season training with Liverpool this week and Klopp had backed his goalkeeper, saying the head injury "explains" his performance in the second half of the final.
Klopp told Liverpool's official website: "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."