The 18-year-old was blooded due to a hamstring problem for Hayden White and concussion for Matt Preston but came through with flying colours.
“He deserved that chance. We had no hesitation in using him,” said Flitcroft.
“I saw him train with the first team in Portugal and what he produced. He is honest and he is sincere.
“On Saturday it was a colossal performance against strikers who are 6ft 5ins and don’t give you a minute.
“It’s not as though he’s gone into a game where it’s not blood and thunder.
“He’s come into a game where he has been tested - and he has stood up to that test.”
However, the game ended in a 1-1 draw and the manager added: “I was gutted for him as you remember your debut, you always do as a player.
“I wanted a win for him. I told the players they’d let him down not getting that debut win for him.”
Gibbens, 18, certainly enjoyed his first game.
“I thought I had a good game but there’s always areas for improvement,” he said.
“Anything can happen in football so you’ve always got to be prepared. I’d like to have thought it was going to happen, working hard every day to try and get that chance, and today it came.
“It was a tough game. I thought we dominated the first-half and we probably should have seen them off but then second-half we were getting peppered at the back so when they got their chance they took it.
“He (Harry Smith) is a big lad and when you come up against big strikers and you are young you’ve just got to battle them and do what you can.”