Gillingham boss Neil Harris has said his players will write their names in FA Cup folklore if the newest League Two club beat Leicester City.
The Foxes, winners in 2020-21are the big favorites to reach the fourth round against opponents who have not won a league game since October 1.
The encounter is live on BBC One and Harris said: “These games are for heroes.
“People are going to tune in to see if Gillingham can cause one of the biggest upsets of all time.”
Gillingham are five points from safety in League Two, but Harris said Saturday’s tie is no distraction from trying to stay in the Football League.
“The bottom of the Football League playing recent Premier League champions is the beauty of the FA Cup,” added the former Millwall boss.
“That’s why the fans love the FA Cup because the underdog has an opportunity. The FA Cup is special and is synonymous with the English game.”
Gillingham, who won at Brentford in the Premier League in the Carabao Cup in November, beat non-league AFC Fylde and Dagenham & Redbridge to reach the third round.
Harris was Millwall’s manager when they knocked out Leicester on their way to the FA Cup quarter-finals in 2016-17.
Striker Patson Daka could return for Leicester after recovering from a hamstring injury.
Leicester are 13th in the Premier League table and come to Gillingham after three straight league defeats.