The Brazil playmaker, 25, missed Liverpool’s 3-3 draw at Watford on Saturday due to a back problem.
But he submitted a transfer request the day before the game and is reported to have been the subject of an unsuccessful £90 million ($116.7 million, 99 million euros) bid from Barcelona.
Barcelona have targeted Coutinho, as well as Borussia Dortmund’s French winger Ousmane Dembele, after selling Neymar to Paris Saint-Germain in a world-record 222 million euros ($261.7 million) deal.
Liverpool’s American owners Fenway Sports Group issued a statement last Friday saying Coutinho would not be sold at any price.
Liverpool manager Jurgen Klopp has said he has no control over the situation.
“As a manager of a football club I have bosses, and if the bosses decide, for example, we sell a player or we don’t sell him, then I have to accept it,” he said after the game at Watford.
“The only thing is I work with the players I have. That is what I’m always doing.”
Liverpool play Hoffenheim at Rhein-Neckar-Arena on Tuesday and welcome the German side to Anfield next Wednesday, with a place in the Champions League group phase at stake.
Liverpool striker Daniel Sturridge will also miss the trip to Germany due to a thigh injury.