Ferguson is well aware that in the past Exeter and Burton Albion have both stopped the Reds from scoring when they have held them to 0-0 draws in the same competition.
But Fergie is sure that something like that won’t be happening in this tie.
"You talk about the FA Cup dying and it's not dying as long as you have got giant-killing acts like Crawley have produced," he said.
"Every manager will tell you, you don't want to be a casualty.
"We lost to Leeds last year and it wasn't easy to take that. They deserved to win on the day. They were up for it and made it a cup tie.
"It will be the same tomorrow. Crawley will get stuck into us and there's no other way for them.
"We have got good experience of playing sides like Crawley over the years like Exeter and Burton Albion.
"It's a reminder shocks can happen and almost did against those two teams. But I think the quality we have tomorrow shouldn't give us the same worry."