Absent Liverpool manager Jurgen Klopp was "delighted" as the youngest team in the club's history beat Shrewsbury to reach the FA Cup fifth round.
Klopp decided to miss the fourth-round replay because it fell during the Premier League's winter break.
A Reds side with an average age of 19 years and 102 days set up a tie at Chelsea with a 1-0 win.
"There was a message at half-time and at full-time [from Klopp]," said under-23s boss Neil Critchley.
"There was a message before the game that Chelsea away could be an opportunity for one or two of them and they put in a performance tonight."
There was at least one of Klopp's senior players in the sell-out 52,399 crowd, with James Milner offering his support sat behind the home dugout.
"He trained with us yesterday and he asked whether he could come along," added Critchley, who oversaw the game for Liverpool.
"He was giving words of advice, he was getting right behind the players. He was vocal in the dressing room. He was animated. He was vocal behind me, I could hear him."
Ro-Shaun Williams' own goal was enough to send a Liverpool side containing seven teenage outfield players through against their League One opponents.
Liverpool right-back Neco Williams, whose long ball forward led to the goal, said it was a night that his team-mates would remember for "a long time".
The result means the Reds are still in the chase for three additional trophies, having already won the Club World Cup and Super Cup.
They have a 22-point lead at the top of the Premier League and are in the last 16 of both the Champions League and FA Cup.
"The lads were excellent and hopefully we will do the same against Chelsea in the next round," said 18-year-old Williams.
"Our aim is to win the FA Cup. I think the [senior] lads will have been extremely proud of us and hopefully us young players will get a chance again."
Aged 19 years and five days, Toxteth-born Curtis Jones became the youngest first-team captain in Liverpool's history.
"All the boys went out there and showed belief, character, showed everything that the manager looks for in his players," said Jones.
"I was grateful to become the youngest captain of the team but most importantly we came away with the win with a great performance.
"The boys showed heart, character and a hard decision for the next game."
Former England captain Alan Shearer said "it doesn't sit right with me" that Klopp missed Tuesday's match.
The German said last week he "decided three weeks ago we would have a mid-season break based on a letter we got [from the Premier League] in April 2019".
Top-flight teams were all due to have two weeks off in February but the 2-2 draw in the original tie meant the replay fell within that period, prompting his decision to miss the match, along with his entire senior squad.
"I understand Jurgen's point in terms of his players having the break they were told they'd have," said Shearer on BBC One.
"He is the manager so he can put whichever team he wants but it doesn't sit right with me - he should be there. He should be at the ground giving the support to those young players."
Former England keeper Rob Green, speaking to BBC Sport, said Klopp's decision not to field his senior players and stay away was "clever mind games".
"Coming from Germany, he thinks we're crazy playing all these games, so it's a really interesting quandary and one where you're thinking he's got the upper ground here," added Green.
Former Birmingham and Crystal Palace striker Clinton Morrison also believes Klopp should have been present.
"If I was one of those youngsters, I would've liked Jurgen Klopp to have been there, win, lose or draw, to have put an arm around me and say I had done well," said Morrison.
"But he's made his decision and he's one of those managers that has credit in the bank because he's been so good."
Shrewsbury boss Sam Ricketts said before the replay that the League One club missed out on making more money from it.
The Reds cut ticket prices to £15 for adults and £1 for children while the game was not shown live on television.
"We're going to generate some money from this but nowhere near what it could've been," Ricketts told BBC Radio 5 Live.
"It had the potential to be a real legacy for the club and for us to put some infrastructure in place but it's still more then what we would've got without a replay, so we'll look at that on the positive side."
Speaking about the game, Ricketts said his players "could not get near" Liverpool "to impose ourselves".
He added: "It is game 39 for us and it caught up with us. We could not get up to the physicality level."