The jockey steered Asgarda to victory in the $1 million feature at Royal Randwick, defying the $26 odds to secure the biggest triumph of her career.

Brett Robb's Gallant Star finished second, with Rapbidash, ridden by Nisbet's brother in law Tommy Berry, in third.

Asgarda is trained by former The Canberra Times journalist Doug Gorrel. The veteran previously trained out of Thoroughbred Park but is now based in Wagga.

The race featured the top horses from around country NSW who qualified via a series of heats across the state.

Nisbet secured Asgarda's place in the final in the Albury qualifier in February.

The race featured a who's who of top city jockeys, with Craig Williams and Nash Rawiller among the riders.

Gorrel, however, opted to stick with a successful formula and booked Nisbet for the final.

While the punters discounted the mare, Gorrel's decision paid off and Nisbet delivered a memorable victory.

"I can't thank Dougie and the [owners] enough," Nisbet told Channel 7. "They could have very easily put a city jockey on but they stuck loyal to me and I'm so glad I could repay them.

"Me being on her probably blew her out in the market a bit. If a city jockey was on her she would have been a lot shorter and given more of a chance but she's a ripper little filly and she just tries her hardest."