Player-manager Ian Dunn admitted naive defending, inexperience and a lack of leadership cost Pinchbeck United.
The Knights were knocked out of the Buildbase FA Vase as they conceded five times in the second half against Holbeach United on Friday night.
Striker Corey Kingston missed a hat-trick of first-half chances before the Tigers took control.
Dunn reflected: “We should have been 2-0 up and it would have been a different game in the second half.
“Mitch Griffiths had a half chance and buried it so that’s a massive learning curve for these guys.
“We acquitted ourselves well but then we were very naive and it showed in the end with the amount of goals we conceded.
At 2-0 we had to chase it and they punished us.Ian Dunn
“Heads went down and we lacked a bit of leadership at the back.
“At 2-0 we had to chase it and they punished us.
“They reacted to every ball which dropped in the penalty area.
“We wanted nights like this with a big crowd and it’s a great achievement for the club to come this far.
“Holbeach’s squad is full of UCL experience and it’s pleasing that we hurt them at times.
“But our naivety and inexperience showed in the end.”
Assistant manager Allan Ross added: “The night was all about Pinchbeck playing in a FA competition and it felt like a proper tie.
“We had watched Holbeach four times so we were prepared for their quality.
“We still have our squad from the Peterborough League Premier Division because we’ve only brought in Andrew Tidswell who recently played at a higher standard.
“We kept the team together and as a club, it’s a proud moment to be involved in the FA Vase.
“It was great to see that amount of people watching a local game at this level and so many supporting Pinchbeck.”
The Knights return to action on Wednesday night at Blackstones in the ChromaSport & Trophies United Counties League Division One.