On a tough day for punters at Caulfield, the David and Ben Hayes and Tom Dabernig-trained six-year-old was one of just two favourites to get the chocolates, hitting the lead with 150 m to go and holding on to beat Street Sheik by 0.75-of-a-length.
It was the fourth win of So Si Bon's 49-start career, and Ben Hayes was thrilled with the drought-breaking effort.
“It was an easy watch today, the race worked out beautifully, he just landed in a great spot, (jockey) Mark (Zahra) got him to settle and when he relaxes like that in his races that's when he finishes off best,” he said.
“He's a cheeky horse, I'm sure Twitter is going crazy, when everyone writes him off he wins. It's a really big thrill, and the owners are very patient, I'm sure they're dancing around and are very happy.”
Hayes suggested a family discussion would be necessary before So Si Bon's next race would be targeted.
“I know we've said it 100 times, but since he's been a gelding he's been an absolute pleasure to train, very easy and he does everything you want,” he said.
“I'll have to have a team meeting with Tom and Dad — I'm sure there's a couple of other races around.”
Later the Euroa-based team would make it a double as Lankan Star stormed home to claim the $120 000 Gold Dash.
The three-year-old was ninth and trapped well behind the leaders as they went around the bend, but found a run and swooped home to hit the front with 50 m to run.
Lankan Star ran second in last year's Blue Diamond before an underwhelming ninth in the Golden Slipper, with Saturday's triumph her first win in more than a year.
She paid $19.10 for the win.
Earlier, Lindsay Park had another two placings; Sikorsky ran second in race one, while Pure Scot ran third in race two.