Sheffield search for their 14thwin in 16 games when they host Whitehaven on Sunday, but Aston is aware of the dangers.
Aston said: “When you’re top of the league you’re a target and teams raise their game.”
Whitehaven coach Dave Woods has doubts over Jamie Rooney (hamstring) and Chris Fleming (hamstring).
Woods said: “We know what quality Sheffield have got and that we’ll need a big effort this week.
“We beat them in the first round at home and had a game-plan that we thought worked. Hopefully we can get out there, get in their faces and keep some pressure on their main men.”