That means Jurgen Klopp will be without his star man for the busy Christmas period.
The Daily Mail claim Coutinho has suffered ankle ligament damage and is expected to miss 5-6 weeks of action.
That is bad news for Liverpool as the Brazilian has been in stunning form this season, scoring five goals and providing five assists in the Premier League.
And it also rules the 24-year-old out of the Merseyside derby on Monday, December 19.
Coutinho was injured after a clash with Sunderland midfielder Ibrahim Ndong in the 2-0 win on Saturday.
A Divock Origi effort and a James Milner penalty secured all three points for the Reds.