"He began pretty well today but then he got bashed by another horse and got himself in a bit of a tangle,” Dunn said.
"That put me back further than I'd anticipated, my plan was to follow Craig Williams (Tycoon Tara).
Chautauqua ($2.60 fav.) gave the leaders eight lengths start passing the 600 metres before accelerating around the field to outclass his rivals, coming away to defeat Flamberge ($5.50) by 1 1/2-lengths with the three-year-old Furnaces ($5.50) a further 1 1/4-lengths away third.
Dunn said the five-year-old has matured mentally since the autumn.
"We haven't put much pressure on him yet. The race today was unknown territory for him, a thousand metres around the Valley,” Dunn said.
"I was off the bridle at the 800 metres but from the 600 he just started to grow underneath me and just took me there.
"It took a little while for him to wind up but to see him do that was extraordinary.
"He handles himself so much better now. The little things he was doing wrong before he's not now.
Wayne Hawkes, who trains Chautauqua in partnership with father John and brother Michael, said he was not concerned when Chautauqua was towards the rear through the early stages/
"It wasn't where you'd want to be with a normal horse, but he's no normal horse,” Hawkes said.