Liverpool suffered a potentially huge early-season blow as Alisson was removed with an injury in the first half of their season opener against Norwich City.
Following the game Liverpool boss Jurgen Klopp increased the club's fears by saying that the goalkeeper's injury "doesn't look too good."
The goalkeeper slipped while taking a quick goal kick and grabbed at the back of his leg before falling down to the turf in pain.
After staying down for several minutes, the Brazilian limped off the pitch slowly and was replaced by Adrian in the 39th minute, with the Reds already up 3-0 at Anfield in a game they would go on to win 4-1.
But the 32-year-old could now be set for an extended period in goal for Liverpool based on Klopp's words after the game.
"The goalkeeper situation has a shadow over it," Klopp told Sky Sports.
"He thought something hit him, so that's not a good sign. He thought that but that's not what happened, sportsmen will know what I mean.
"It obviously shows it's more than just a strain. We don't know exactly but it doesn't look too good."