"He ran against Red Cadeaux on three occasions and beat him every time " he was a pretty serious horse," O'Sullivan said.
The stable also won the group one Windsor Park Plate two years ago with another former Hong Kong performer, Pure Champion.
"This one is maybe a little bit more special," O'Sullivan said.
Jockey Craig Grylls, who also rode Pure Champion, was happy to let the 9-year-old Willie Cazals lope along at the back of the field.
Willie Cazals' sustained finish saw him collar the favourite Humidor close to home with Hasselhoof finishing well for third ahead of El Pescado and the well-supported Rasa Lila, who had her chance.
Meanwhile, the Donna Logan and Chris Gibbs-prepared Mongolian Falcon upstaged his rivals with a runaway victory in the group two Sacred Falls Hawke's Bay Guineas.
The 1400m event had been widely billed as a match race between the unbeaten pair of Heroic Valour, a stablemate of Hall Of Fame, and Stephen Marsh's Ugo Foscolo but it was the Inner Mongolia Rider Horse Industry-owned son of Fastnet Rock who left them all in his wake.
Innes allowed Mongolian Falcon to stride to the lead and they strolled away in the run home for a sublime victory.
Jon Snow turned in an encouraging effort for second ahead of Heroic Valour with Ugo Foscolo, who raced keenly, back in sixth spot.
- NZ Racing Desk