Liverpool's kids tackle League One Shrewsbury tonight - and Anfield hero James Milner has challenged them to show what they can do on the big stage.
Jurgen Klopp's side looked to be cruising into round five after going 2-0 up in the original tie.
But things quickly fell apart towards the end, with the Shrews earning a 2-2 draw and a replay on Merseyside.
A full house is expected at Anfield tonight and Milner can't wait to see Liverpool's young guns go for it, with manager Klopp and his senior side having a fortnight off for the Premier League's mid-season break.
Milner tweeted: "Full house tonight at Anfield - show them what you can do, lads #FACup #YNWA"
Toxteth-born teenager Curtis Jones became Liverpool's youngest captain at 19 years and five days after being handed the armband to lead the youthful team in the FA Cup fourth-round replay
Under-23 manager Neil Critchley is in the dugout, and his team contains four players - Jones, Harvey Elliott, Neco Williams and Pedro Chirivella - from the original tie in Shropshire.
With youth team players Adam Lewis, Jake Cain and Liam Millar all making their senior debuts the starting line-up had an average age of 19 years and 102 days - the youngest in the club's history, beating the side which played at Aston Villa in the Carabao Cup quarter-final in December when the first team were in Qatar.
League One Shrewsbury named 10 of the side which started the original tie.
Liverpool: Kelleher, Williams, Hoever, van den Berg, Lewis Clarkson, Chirivella, Cain, Elliott, Millar, Jones.
Subs: Gallacher, Dixon-Bonner, Boyes, Bearne, Norris, Hardy.
Shrewsbury: O'Leary, Love, Ebanks-Landell, Williams, Golbourne Pierre, Edwards, Laurent, Whalley, Lang, Goss. Subs: Murphy Beckles, Sears, Walker, Udoh, Cummings, Hart.
Referee: Andrew Madley (West Yorkshire)
Kick-off was delayed by 15 minutes, putting it back to 8pm, due to a crash on the M62 closing the motorway for a couple of hours and affecting hundreds of fans fans travelling to the game.