In a race that didn't quite go to plan, Tycoonist ($4) camped just behind the speedy Malkovich ($2.90 fav) and the pair fought out the finish with Tycoonist edging him out over the final stages.
Surreal Step ($7) was another 1-3/4 lengths away third.
Waller's stable representative Charlie Duckworth said they were anxious when more rain fell on Saturday morning as even though Tycoonist had heavy track form, it was in lesser grade than the Listed Hawkesbury Gold Rush (1100m).
"We were slightly concerned the track might have been too heavy," Duckworth said.
"While his stats on a heavy surface look really good, they were at a lower level and a weaker grade.
"We were certainly concerned when the rain fell this morning, but he seemed to get through it well."
Duckworth said the plan had been to ride Tycoonist more quietly but he praised jockey Chad Schofield for using his initiative and getting it right.
"We did want to ride, ideally a pair worse and ride for one last crack but you can't knock Chad's ride, he won," Duckworth said.
"It proved the right move, a winning ride.
"It's good to see Chad ride us a winner. He's probably struggled a little bit to find his feet in Sydney with a couple of injuries and a couple of setbacks, but he is a world-class rider, as is anyone who comes down from Hong Kong."
Duckworth believes the best is still to come for Tycoonist, who will continue to chase more feature race success into the winter.
"Tycoonist is on the up and I'm sure there is a nice one in him," he said.