In the $100,000 NZ Trot Free-For-All he drives the best horse in Sundees Son, his concern being the Trotter of the Year's mental rather than physical condition.
But Cup day is about the Cup and while Dunn's father Robert trains both Classie Brigade and Henry Hubert, it is the former who has the manners to be the kingmaker.
Classie Brigade began brilliantly before leading throughout in the Kaikoura Cup last Monday but that was against weaker opposition on a leader's track in a race 800m shorter.
With standing start manners concerns over some on the front line, especially the Australians, Classie Brigade could well lead again first time into the Addington straight today.
So what would Dunn, who has parked out his arch rivals the All Stars more than any driver in New Zealand in recent years, do?
"I don't think you can make those decisions in advance and of course he would have to step away quickly first," says Dunn in the expected response.
"And he [Classie Brigade] is a good horse. You would like to think he could win the race."
But dig deeper and Dunn admits that the two favourites Spankem and Thefixer might be better than his charge. He won't say it, but you get the feeling if either came seriously looking for the lead Dunn would take the short way home.
A decision like that from Dunn, or any rival driver, would seem to hand the Cup to whoever out of Spankem or Thefixer got their first and could set up a lead-trail scenario for the favourites.
While all of that makes Classic Brigade a great place bet at $3.50, in the Sires' Stakes things look trickier from barrier one for Above N Beyond.
He is good, maybe really good, but even though it is a sprint the Sires' Final can be brutal for leaders. So Dunn wants to lead early and see how much pressure is poured on.
"It is easy to think I would hand to One Change [barrier two and favourite] and get the trail but I doubt he will be the first horse there and anything on the front line could come out fast.
"So it is a really hard to race to predict. But I'd rather be barrier one than nine."
Sundees Son is one on the second line in the trot but that is not as big a concern as the fact he has galloped in his last three public appearances.
"I think it is in his head now and that is a worry," says Dunn.
In the support races Dunn reins four favoured runners, starting with debutante Sugar Loaf in race two.
"She has really impressed me at the trials and has the speed to stay handy early.
"Bonnie Highlander [race three] was really good at the trials last week and I'd rate her the better of our two chances off the front line.
"And Heisenberg [race eight] has to be hard to beat. He won really well at Kaikoura last week and has bounced through that well."
Add in another impressive trialist last week in Belmont Major (race nine) and Dunn is in for a big Cup day. But punters would be smartest to put their big money on him when the smaller money is on the line.
New Zealand Cup Day
Where: Addington, Christchurch.
When: First race 12.05pm today.
What: The biggest harness meeting in the Southern Hemisphere, with three Group 1 races, including the $750,000 New Zealand Trotting Cup.
Who: The Cup has 10 New Zealand and three Australian horses.
Watch: Preview show live on Trackside (Sky 62) from 9.30am, live raceday coverage from 11am. Free to air coverage on Sky 200.
Punt: Tote and fixed odds all races, $50,000 terminating Pick6, head to head and special bet options.
