Preston have won their last five matches in all competitions, with Paul Gallagher and Alan Browne securing their 2-0 home success against Port Vale on Saturday.
Grayson's men sit fourth in the League One table and, although they are nine points behind runaway leaders Bristol City, the Preston coach is convinced they can bridge the gap.
The 44-year-old has become somewhat of a promotion specialist in League One - leading Blackpool, Leeds United and Huddersfield Town to promotion in the third tier.
And he is encouraged with his side's recent form, telling Preston's official website: "We've got players playing with confidence... we've worked extremely hard on certain aspects of the pitch in training.
"[Gallagher] is playing with belief - he's shooting from distance where probably at the early part of the season he might have took the safer option.
"But all of the players are all playing with confidence, right throughout the squad.
"We're playing very well at this moment in time."
Gillingham, who host Tuesday's clash, drew 1-1 at Rochdale on Saturday - extending their winless run to five league matches.
Bristol City are the only unbeaten side in League One this term and Steve Cotterill's men will fancy their chances at home to Bradford City.
Averaging over two goals a game, the Ashton Gate attack - led by Aaron Wilbraham and Kieran Agard, who have eight and six strikes respectively - is proving a match for any side.
Robins' next test comes at Port Vale, still led by caretaker Robert Page. Vale are also in the relegation zone, in 22nd.
Eoin Doyle is comfortably the league's top scorer with 14 and after failing to net against Oldham Athletic on Saturday, he will be fired up for Chesterfield's trip to Colchester United.
Elsewhere, Crawley Town face off against Walsall, while Milton Keynes Dons battle Fleetwood Town and Oldham meet Coventry City.
