Flitcroft takes his npower Championship relegation battlers to the Etihad Stadium on Saturday to face Barclays Premier League champions Manchester City in the last eight, with a Wembley semi-final place the incentive for an unlikely giant-killing.
But the 39-year-old, who will lead the Tykes for the 14th time since mentor and predecessor Keith Hill was sacked at the end of December, insists he has already passed a sterner test.
Barnsley had already been snubbed by Sean O'Driscoll and Terry Butcher in their bid to find a replacement for Hill when a 2-0 home win over Leeds convinced them to give assistant and then caretaker-manager Flitcroft his chance.
Just two defeats in the 10 games since, including FA Cup wins over Burnley, Hull and MK Dons, suggest the Oakwell board made the right decision.
"I think the Leeds game was the biggest," said Flitcroft, younger brother of former City captain Garry. "Knowing that you're fighting tooth and nail to get a job you really want.
"That was the biggest game for me and it probably always will be because the pressure, the intensity, the thrill of whether you're going to get the job or not was something that will live with me for the rest of my life.
"This is a different game. It's one I'm happy for the players to be involved in and I'm happy for (assistants) Micky Mellon and Martin Scott, who was out of the game eight weeks ago.
"Now they're going to be in the dugout competing against the champions of the country.
"There's a lot of excited fans as well, I think there's 6,000 coming and we could quite easily have got rid of 12,000."