The youngest ever Liverpool team to play a competitive game were outclassed in the League Cup in the first of the club's two games in 24 hours.
With Liverpool's first choice squad at the Club World Cup, they were forced to field their youngsters - with an average age of 19 years, 182 days - against Aston Villa and were beaten 5-0.
Under-23 coach Critchley took charge of the Reds as manager Jurgen Klopp chose to prioritise the trip to Qatar.
It resulted in an unsurprising loss at Villa Park, but Critchley was proud of the never-say-die attitude of his players, five of whom made their senior debuts.
Come the final whistle, Villa manager Dean Smith shook the hand of every Liverpool player as they left the pitch, while he and assistant John Terry then visited the opposition dressing room soon after to pass on words of praise.
Critchley said: "That was a special moment. The conduct of the Villa players toward our players all night was first class, and for Dean Smith and John Terry to come into our dressing room and say such complimentary words to our players was a special moment for that group.
"That is something that will live with us for a long time. That was top, top class I thought."
Smith said: "I told them they're a really talented group of players, and they made life very difficult for us. I'm sure there are a number of players we've seen out there who will be playing in the Premier League in three or four years' time.
"And losing 5-0, sometimes that's all you remember, rather than the performance, so I felt it was important."
Although Liverpool started superbly, with Villa goalkeeper Orjan Nyland making two key saves from Harvey Elliott and Herbie Kane, a fortuitous free-kick from Conor Hourihane in the 14th minute and a freakish own goal from Morgan Boyes three minutes later put Villa in control.
A brace in the closing eight minutes of the first-half from Jonathan Kodjia, and a second-half added-time strike from Wesley added gloss to the result for a Villa side now facing a semi-final for the first time in six years.
Asked whether Klopp had offered any comment, Critchley said: "We had some information at half-time from the manager, basically he told us to keep playing the way we were playing, to keep being brave.
"He was watching (in Qatar) with the staff and the players, and I'm sure he will be proud of the way we played tonight."
It was Liverpool's first domestic loss of the season but Critchley added: “For long periods, I thought we were well in the game.
"You get a harsh reality of the quality you are facing. We ran out of a little bit of legs and steam in the second half, which was understandable but it was an incredible night.
“I don’t think anyone wanted it to end. They said how difficult we made it for them, that we have some really good players, to keep going and wished us all the best for the future. That will be a moment that I remember and the players remember for the rest of our lives.”
The other three quarterfinal matches take place on Wednesday, with Manchester City continuing their defence at third-tier Oxford.
Manchester United are at home to Colchester, while there is an all-Premier League match between Everton and Leicester
