Boss Jurgen Klopp has confirmed he will draft in Karius for the Reds' return to the Champions League as he continues to chop and change between Simon Mignolet and the German.
Karius was brought in to face Arsenal last month but it was Mignolet between the sticks for the defeat to Manchester City at the weekend, and Klopp says he will continue to rotate in order to keep each shot-stopper fresh.
"Why do we think number one, two, three is fixed until the end of all days? I don't want to bring that in doubt but how can you ask if he's number one? By the way, it's not that he shouldn't be number one," said Klopp
"If they train bad they don't deserve a game, but they both train really well, they keep the level really high.
"If we don't give them a game then every year we have to find a number two, 33 years old, who still can catch a few balls and doesn't want to play any more - that's really difficult, to find someone like that.
Meanwhile, Coutinho will be in Liverpool's squad for the first time this season after his back injury and failed attempt to force a move to Barcelona.
Winger Mohamed Salah sat out training on Tuesday as a precaution because of illness but is expected to rejoin the squad on Wednesday, while centre-back Dejan Lovren is set to return at the expense of Ragnar Klavan.
Provisional squad: Karius, Gomez, Matip, Lovren, Moreno, Henderson, Can, Wijnaldum, Mane, Firmino, Salah, Mignolet, Alexander-Arnold, Klavan, Robertson, Milner, Oxlade-Chamberlain, Coutinho, Sturridge, Solanke.