Graham Alexander was delighted after Fleetwood dug deep to beat Rotherham 2-1 to progress to the JPT northern area final.
Jeff Hughes put the Cod Army ahead after 19 minutes before Rotherham grabbed a deserved equaliser 10 minutes after the break through Nouha Dicko.
Full-back Conor McLaughlin's stunning strike 20 minutes from time and two injury-time saves from Fleetwood goalkeeper Scott Davies set up a two-legged clash with Sky Bet League Two rivals Chesterfield for a place at Wembley.
It was Fleetwood's fourth victory over Sky Bet League One opposition in this season's competition, following wins over Tranmere, Crewe and Carlisle.
"The lads have really responded to the challenge of playing sides from a higher division," said Alexander.
"It was a tough game, it was to and fro. We took the lead, they got an equaliser but the response after that was fantastic.
"The goal that won it was out of this world."