The Eagles have won all four clashes between the sides this year, but Aston is far from complacent.
He said: “This is a one-off, winner take all. Dewsbury have had a good end to the season, winning their last three, and they’ll be confident.”
Dewsbury coach Glenn Morrison said: “We’ve been playing finals footy for the last four or five weeks now, and we’ve shown a lot of character all year.
“We’ve had people busted and playing out of position, but the spirit at the club is fantastic.”
He added: “Sheffield have been in finals and won big matches for years. We’re expecting a very tough battle, but we’ve played them a number of times this year and been in front at various stages.
“If we play the full 80 minutes to our best ability, we’ll give ourselves a chance.”