The Rams are currently fifth in the second tier, just five points off an automatic promotion spot after winning for the first time in nine matches in the league against Brentford on Saturday.
After the East Midlands club's dramatic collapse last season, Wassall knows that it is crucial that his side take confidence from that victory and get the momentum rolling again.
He said, as quoted by the club's Twitter account: "The whole squad contributed on Saturday and the win has given everyone at the club a lift. Confidence is a massive part of any footballer's life, ability alone isn't enough.
"We aren't getting carried away [but] the win has given everyone hope and belief - we want that to continue in tomorrow night's game."
Under current Newcastle United manager Steve McClaren last season, Derby crashed from top of the Championship at the end of February to missing out on even a play-off spot after winning just two of their final 13 matches.
The caretaker boss continued: "Andi Weimann was ill at the weekend but he trained today so that is a boost for us ahead of the match.
"George Thorne trained yesterday and today so he isn't far away from being back in contention for a place in the team."
County take on Blackburn Rovers at home on Wednesday night before travelling to face Wolves at Molineux next weekend.