Liverpool have been dealt a major blow with the news that goalkeeper Alisson Becker could be ruled out until after the next international break.
The Brazilian has suffered a muscle injury in training and is set to miss Saturday's meeting with Bournemouth as well as next week's Champions League return leg against Atletico Madrid.
The Reds will be aiming to overturn a 1-0 deficit from the first leg in Madrid last month when they face Diego Simeone's men on Wednesday.
"Unfortunately, Alisson is out," Klopp confirmed. "Hurt in training before the Chelsea game. Little incident, we all thought it was nothing."
Alisson was left out of the squad against Chelsea - as was the plan anyway - with Adrian returning to the starting line-up for the 2-0 defeat at Stamford Bridge.
But Liverpool discovered Alisson's injury was worse than first feared after assessing the damage on Wednesday.
"Scan the next day and they found something, so now he's out," Klopp continued. "We'll see next week for sure.
"Small muscle. You could all [do] your work still, but for a professional goalkeeper it is slightly different."
Klopp was initially coy about the length of time Alisson could be sidelined, but later admitted his No.1 is guaranteed to miss the return leg against Atleti.
Asked if his lay-off would extend beyond the Merseyside derby clash with Everton on March 16, he added: "I don't want to say no but I don't know if he will be available for that.
"He's not available for the next week, not for tomorrow and not the next week. Then we have to judge the situation.
"I would say after the international break he is back 100 per cent, whatever we can get before then, we will see."
