Mane reportedly broke his thumb in training prior to his country's Africa Cup of Nations qualifier against Sudan on Tuesday.
Liverpool head to Huddersfield Town on Saturday (Watch live, 12:30 p.m. ET on NBC) and although Klopp will likely be able to rotate his squad and still get a win against the Terriers, Liverpool have a hectic few weeks coming up with UEFA Champions League and PL games coming thick and fast.
The nature of the issue means there is less optimism about Keita's condition in comparison to the other players who handed Jurgen Klopp injury scares over the worldwide break.
While Jurgen Klopp is expected to be able to call upon two of his most important players on the weekend, doubts remain over the fitness of Sadio Mane and Naby Keita.
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Speaking on Thursday, Wagner played down suggestions that Liverpool might be without a string of top names after the likes of Mohamed Salah (groin), Virgil van Dijk (rib) and Naby Keita (muscle) suffered injuries on worldwide duty.
But Wagner is not convinced any of them will miss the match at 5.30pm on Saturday.
However, Huddersfield will be hoping to at least hold Liverpool to a draw, with some reports making it known that five of Klopp's key players will not be available for the match.
'Now we have a great opportunity, a wonderful game in front of our fans against a very strong side, where we can hopefully perform at the same level (as our last game). But training looks tremendous; he obviously enjoys playing football.