The Reds' first-choice goalkeeper sustained a hamstring injury late on in Saturday's high-profile 1-1 draw with Premier League title rivals Manchester City, needing treatment before playing on and limping off at the full-time whistle.
Liverpool boss Jurgen Klopp has since confirmed following a scan that the issue is not as serious as first feared but still "bad enough", with Alisson definitely set to be sidelined for this evening's visit of LASK in the Europa League and the top-flight meeting with Fulham on Sunday.
Alisson also seems likely to sit out against Sheffield United and Crystal Palace next week, but could be in a position to return for the final Europa League group game against Union SG on December 14 or in the top-flight showdown with fierce rivals Manchester United three days later.
Liverpool also saw Jota limp off early in the second half against City with a muscle issue that is more serious than Alisson's as he faces a longer spell in the treatment room, where he joins Andy Robertson, Thiago Alcantara and Stefan Bajcetic - none of whom are expected back in action before the New Year.
"With Alisson it is a bit lesser so we will have to see," Klopp said on Wednesday.
"He's not going to play tomorrow or on Sunday, probably not the week after, then he could be kind of OK, but Diogo will take a little bit longer.
"We don't know exactly how long but it is a bit more serious."
Alisson's deputy Caoimhin Kelleher has started all but one of Liverpool's Europa League group games so far this term and Klopp said he would have done so again tonight regardless of the Brazilian's injury.
He is now looking for the Republic of Ireland international to step up and show his quality with an extended first-team audition over the coming weeks.
"He would have played anyway and deserves his opportunity to get a few more games and hopefully he can show his full potential," Klopp said.
Having suffered a shock defeat by Toulouse in their last Europa League outing, Liverpool are looking to get back to winning ways on the continent against LASK - with a point enough on matchday five to secure progress with a game to spare.
Table-topping Liverpool will be confirmed as winners of Group E if they beat bottom club LASK tonight and Toulouse do not overcome Belgians Union SG at home, meaning a direct route into the last 16 and no play-off round to contend with in early 2024.
Klopp had hinted at ringing the changes against the Austrians as he bids for "fresh legs" with such a hectic fixture list coming up.
"I will line up a team with fresh legs who want to go for it, enjoy the game and will really fight for a result," he said.
Time and date: 8pm GMT on Thursday November 30, 2023