Brazilian goalkeeper Alisson kept 21 clean-sheets for Liverpool in his first Premier League campaign
Liverpool manager Jurgen Klopp said goalkeeper Alisson's calf injury "cast a shadow" over the 4-1 win against Norwich in the Premier League season opener.
The Brazilian suffered the problem as he took a goal-kick towards the end of the first half, and will now miss next week's Super Cup match against Chelsea in Istanbul.
"It felt like something hit him and that's not a good sign," said Klopp.
"He will not be ready for Wednesday."
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Dominant Liverpool thrash Norwich
Action as it happened from Anfield
Alisson was a key figure for the Reds in his debut season, helping them win the Champions League and take the Premier League runners-up spot.
The 26-year-old former Roma player was replaced by new signing Adrian, a free agent in the summer after he was released by West Ham.
The Spaniard made a great save from Moritz Leitner but conceded a goal in the 64th minute when Temmu Pukki fired in for Norwich.
Klopp added: "Adrian was completely relaxed and did what he had to do. He's a good keeper, calm on the ball and a good shot stopper. That's why we signed him."
Liverpool's third-choice keeper Caoimhin Kelleher is recovering from minor surgery on a broken wrist.
Source: bbc.com