Virgil van Dijk has transformed Liverpool's defensive record in almost three years since his arrival - so how much will his absence hurt them?
The Netherlands international, 29, faces surgery and a lengthy lay-off after suffering anterior cruciate knee ligament damage during Saturday's 2-2 draw at Everton.
"It's a huge blow," former Liverpool defender Stephen Warnock told BBC Radio 5 Live. "It will definitely hinder Liverpool's defence of the title."
Liverpool paid £75m, then a world record fee for a defender, to sign Van Dijk from Southampton in January 2018. Since then, they have won both the Champions League and the Premier League.