Salah and Mane will be involved at the Africa Cup of Nations, which is being staged in Cameroon, through January. Mane will be in action first, when Senegal play Zimbabwe on January 10 with Egypt's campaign starting against Nigeria 24 hours later.
Discussions are ongoing with both nations and Klopp, whose side face Wolves on Saturday, said: "It's not decided yet.
"I am an optimistic person so I hope so, but it's not written in stone, not completely in our hands."
Liverpool have long been resigned to being without players who have scored 28 goals between them so far for Premier League games against Brentford and Crystal Palace - they could potentially miss two FA Cup games and the Carabao Cup semi-final also - but are desperate for them to face Chelsea.
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