But despite leading the Kingstone Press Championship table with 14 wins from 16 games, Aston insists his side still have plenty of work to do.
He said: “We’ve got big games coming up and we’ve got to be better defensively.”
Dewsbury will be without Aaron Brown, who has succumbed to a couple of knocks he has been carrying for a number of weeks.
But Rams coach Glenn Morrison remains in confident mood after seeing his side win four of their last five games.
Morrison said: “It’s knockout rugby so it’s anyone’s game – we saw that in the last round against Halifax when we had no pressure on us and got a result.
“It’s the same again this week: everyone will be thinking Sheffield are the form team of the competition.
“It will be tough, but we’ll go in there ready to play our own game and we’ll see where that gets us.”