Lee Johnson has said his side must earn the right to get promoted and will come up against a good Gillingham side this weekend.
The Gills come into the game unbeaten in three - having drubbed Crewe Alexandra 4-1 in midweek.
The Black Cats will be looking to build on their back-to-back wins by repeating the feat on home soil.
Speaking ahead of the tie, Johnson said: "First and foremost you always look at the manager. Steve Evans is a very successful manager particularly at this level.
"His sides are always combative and competitive - we've got to earn the right. They're in good form. They beat a very good Crewe side convincingly in midweek and pressed really high which is a slight tweak to their gameplan.
"I like their midfield I think they've got some good players in there - the likes of Slattery and Dempsey. They've got their forward threats with Oliver up top.
"A player I know well is Cundy at the back - he's a Bristol City loanee. He's a player we signed from Bath.
"We know enough about Gillingham and Steve Evans - enough about their players to know that this is a really difficult game for us and one we've got to be on absolute top form to get the result."
