Manager Jurgen Klopp immediately warned that the the lay-off would "not be a short one", reiterating again on Tuesday that things did not look good for the experienced centre-back as Liverpool anxiously awaited scan results.
Matip missed Wednesday night's 2-0 win over struggling Sheffield United at Bramall Lane that saw the Reds cut Arsenal's title lead back down to two points, with Klopp subsequently confirming the club's worst fears.
"It's an ACL, ruptured, so that's what I unfortunately expected from, that's what it looked like," he said. "Very unfortunate, but that's it."
Matip is now expected to miss the rest of the 2023/24 season and may even have played his final game for Liverpool with his current contract on Merseyside due to expire next summer.
Liverpool remain Arsenal's closest title rivals after a hectic midweek round of Premier League action, with Aston Villa now third and only two points behind the Reds after leapfrogging defending champions Manchester City with a stunning 1-0 victory at Villa Park on Wednesday.
Last season's Treble winners have now gone four league games without a win, though Klopp insisted it would be a massive mistake to write them off at this stage.
"If someone writes City off that would be the biggest joke in the history of football, that makes no sense," he said. "Arsenal are fighting, the next game starts from 0-0.
"I have no clue where it (the title) is going to end up. It is so difficult and intense with all the games coming up. Ask me again in April."