Liverpool manager Juergen Klopp said the COVID-19 outbreak which forced the postponement of their League Cup semi-final first leg against Arsenal last week included many false positives.
The win moved Juergen Klopp's side above Chelsea in the table and 11 points behind leaders Manchester City with a game in hand.
Arsenal became the highest-profile casualties of the FA Cup third round as the 14-time winners lost 1-0 at Nottingham Forest, but Liverpool and Tottenham Hotspur avoided early exits after scares against lower-league sides on Sunday.
Hazard extra-time goal sends 10-man Real Madrid through to Copa del Rey final.