And the German tactician said that the former Schalke 04 defender will miss the game against Massimo Carrera’s side.
"He has hurt his muscle. I don't know how long exactly he'll be out, but he's definitely not playing Wednesday," Klopp told club website.
"A month? No, I don't think so. But as always, it's possible. We have to wait.
"But it's possible that it will be shorter. We will see."
Matip has made 17 appearances in all competitions for Liverpool this season, scoring one goal.
Jurgen Klopp’s side currently sit atop the Group E standings with nine points from five games played. But they need to grab a positive result against Spartak Moscow to confirm their spot in the Knockout phase of the Champions League, with second-placed Sevilla and Wednesday's visitors breathing down their neck.