Preston have collected just three points to lie second bottom of the Championship after seven games.
Martinez said: "Darren Ferguson is working with a new project and players and that is going to take time.
"I have seen them play three times and they are not far away from getting results.
"It is just a matter of time before they get some positive results and into a good groove, but hopefully after tomorrow.
"In a cup competition it is going to be completely different. They are going to come here with great desire and nothing to lose.
"It is going to be a welcome distraction from the league and that could make them very dangerous."