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The Reds failed to get clearance from Fifa on whether he could play for his club during the African Cup of Nations.
Matip, 25, 'refused to play' for Cameroon after being named in their preliminary squad.
Liverpool boss Jurgen Klopp hinted he would select Matip regardless but chose not to after taking legal advice.
Klopp says he has been told that world governing body Fifa will decide by Friday whether an investigation into Matip's situation is necessary.
Matip, who signed from Schalke last summer, has not played for Cameroon since 2015 and was not included in their final 23-man squad for the Cup of Nations.
But Fifa regulations state a player may be blocked from playing for his club if he refuses to play for his country.
The player could miss six to eight games for Liverpool if he is not made available until the end of the competition.
Should Cameroon make it to the final on 5 February, Matip would not be available until Liverpool host title-chasing Tottenham in the Premier League on 11 February.
Liverpool have chosen not to include defender Joel Matip for Wednesday's FA Cup third round replay at Plymouth as the row over his eligibility continues.