Former Derby County striker Marvin Robinson proved an FA Cup gem for Rushden and Diamonds as his late header secured a place in the second round.
The 24-year-old was called-up by manager Ernie Tippett because strike force Gary Mulligan and Drewe Broughton were unavailable, but he proved his worth with the last-gasp winner.
The Bantams went into the game having failed to win an FA Cup tie for five years and the Diamonds' positive start suggested that another early exit could be on the cards.
The League Two outfit showed no nerves against their League One rivals and they made the early running with Robinson almost opening their account in their first attack.
City keeper Paul Henderson smothered his shot on the turn, but there was little to choose between the sides in a drab first quarter.
Bradford's top scorer Dean Windass saw a near post header go straight at Diamonds' keeper Billy Turley before Robinson's presence caused more danger for the home side.
After 19 minutes City skipper David Wetherall had to get a vital foot in to block Robinson's shot, and soon after his low cross was miscued by strike partner Jason Taylor.
Robinson then wasted a great chance when he weakly headed at Henderson after Craig Dove's cross found him unmarked in the City box, and Diamonds midfielder Andy Burgess blazed over from 16 yards just before the break.
Windass came closest to troubling Turley when he volleyed a Nicky Summerbee corner over the bar, but despite Colin Todd's half-time talk the Bantams still looked below par after the break.
His side were reduced to long-range efforts as the Diamonds back line held firm, and the sucker punch came from Robinson two minutes from time.
Centre-half Graham Allen did well to find danger man Dove out wide on the right, and when his cross flew over Robinson dived in to head home from eight yards out.