The Reds are closing are currently top of the Premier League, and they know that if they win their remaining four games they will be the champions.
Rush told The Mirror: "If Brendan can make Liverpool the champions with pretty much the same team that finished seventh last season, then he will be remembered as one of the club's greatest managers.
"Twenty-four years is a long time for a club like Liverpool to wait for the title – too long if we're honest – especially when you look at the money previous managers have been given to spend on players.
"Brendan has had the backing of the owners when he's needed it, but, when you look at the money spent by Manchester City, Chelsea and others, it would be an unbelievable achievement for Liverpool to win the league."
Liverpool can move five points clear of second place Chelsea, with a win over Norwich City later today.