Liverpool goalkeeper Alisson has suffered a hip injury and will miss next week's crucial Champions League last-16 second leg against Atletico Madrid.
Alisson was left out of Tuesday's 2-0 FA Cup defeat at Chelsea as a precaution - Adrian deputised, making an error for the home side's first goal - and scans later revealed the Brazil international would be out for longer than first thought.
Liverpool manager Klopp has confirmed he will miss Saturday's Premier League match against Bournemouth at Anfield and Wednesday's fixture against Atletico, with the Reds trailing 1-0 after the first leg.
Klopp said: "In training before the Chelsea game he had a little incident we thought it was nothing and he was not going to play anyway - he was going to be on the bench.
"And then we thought we wouldn't take any risks so left him out of the squad. He had a scan the next day and they found something.
"He is out next week for sure and then we will see. It is in the hip region, you could all do your work still, but for a professional goalkeeper it is a slightly different situation.
"We have to judge the situation. I would say after the international break 100 per cent. Whatever we can get before that we will see."
Liverpool could see the return of captain Jordan Henderson against Atletico, says Klopp, but Saturday's meeting with Bournemouth will come too soon for the central midfielder.
"Henderson has a chance for Atletico next week, but not for Bournemouth," added Klopp.