Brutal ($5) railed and kicked strongly off the home bend then continued to extend in the straight to win by five lengths over fellow debutant Ronan's Rock, with $2.80 favourite Humma Humma another 1-1/4-lengths away third.
Ronan's Rock ($3.50) was able to regroup and finish second after knuckling shortly after the start.
“He's a nice horse,” Dunn said of Brutal.
“He's always shown us a lot. He's probably in at the right time of year just to get some experience because he's still a kid.
“He had them pretty well beaten a long way from home today.”
Dunn said Brutal will continue to get better as he gets a bit older.
“They'll have a lot of fun with him,” he said.
Co-trainer Wayne Hawkes said immediate plans for Brutal were still to be decided.
“We just wanted to see what happened today, but it's a good position to be in,” Hawkes said.
“When he really quickened and flattened out it was quite impressive I thought.”