Dunn has plumped for Return To Sender, leaving Brent Mangos to drive Geisha Girl.
"It was his first run up there for a while, and he got checked at a crucial time around the last bend," he said.
"In saying that, Geisha Girl has a big drop back in class from what she has been racing. There's no Saveapatrol in here."
The Dunns also have two representatives Defy The Odds and Miss Daisy in race 2, although it was going to be three until they scratched Robbie Burns, who isn't at his peak.
Dunn blamed his drive for Defy The Odds finishing ninth in his first C1 run last week, and he expects to use barrier two to full effect tonight.
"I gave the horse no show from the sectionals they went up front. They sprinted home and I was last at the quarter.
"He lacks a bit of high speed so we'll put him into the race this week."
Miss Daisy was hauled in late last week, although Dunn will consider his tactics when the mobile barrier pulls away.
"She's not that tractable in behind, but in hindsight I would have been better to hand up," he said.
All Royal Gal (R1) is in the same boat as Geisha Girl, dropping back from taking on King Denny at the Ashburton Jewels last month and One Over Da Moon to a C1-C3 trot with junior driver Jack MacKinnon taking the reins.
"Scarrymcleary is going to be the hardest to beat if he steps, but she's trotting great at the moment," he said.
"She normally steps well and hopefully she'll get round in one piece and do a good job for Jack."
Bite The Bullet (R4) is a big 2-year-old who is still learning and will improve from the experience, while Culinary Delight (R5) can make up for her poor manners at Alexandra Park two weeks ago.
Dunn said the best chance for the stable at Addington tonight is Callenberg (R7), who seems to be slowly delivering on his promise with a win last week.
"He ran home in 56 and a bit and went quite nice," Dunn said.
"He's trained on well during the week and it's an even line-up, so he's going to be a nice chance."
Winners at the Park
Best bet: Al Bundy (R6, No 9): Game in defeat behind a group one performer two weeks ago. Can haul in his 20m handicap easily.
Each-way: Majestic John (R4, No 4): Just missed out on clearing maidens last time. Should be handy from his draw.
Roughie: Mighty Sunny (R8, No 9): Was bolting before breaking at Cambridge last time. Can unwind when he behaves.