The Bantams take on Paul Lambert's Barclays Premier League strugglers Villa in the first leg of their semi-final at Valley Parade on Tuesday night and, with good reason, Liverpool-born defender Darby said the npower League Two side will not be overawed.
"Aston Villa are a great side and we're realistic, we keep our feet on the ground," he told Press Association Sport.
"We know the task that lies ahead of us. We've just got to take the positives out of the other games we've played in the competition, use those experiences and take it into Tuesday.
"It's probably one of the biggest matches I've played in to be honest. I played against Arsenal and that was huge, but this is a semi-final of a domestic cup and it's a great achievement for everyone involved and it's going to be a big night for us.
"But we'll approach it in exactly the same way as we did for the Arsenal game."
The Bantams, who won 1-0 at Notts County in the first round, struck two goals in the last six minutes to win 2-1 at Watford in round two and hit back from two goals down to beat third-round opponents Burton 3-2 in extra-time.
Phil Parkinson's side then held Wigan to a goalless draw after extra-time at the DW Stadium before winning 4-2 on penalties and that set up the home quarter-final against Arsenal, in which the Bantams held their nerve again to triumph 3-2 on penalties after the score had been locked at 1-1 at the end of extra-time.
Liverpool academy product Darby, who fired the extra-time winner against Burton, added: "It's always good to play against Premier League players. There's not just (Darren) Bent and (Christian) Benteke in the Villa side that we need to keep a close eye on, they've got a great squad and a great set of players.
"It's going to be another really tough game, but one we're looking forward to."
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