Danny O'Brien is warming to the idea of running Grinzinger Star in the South Australian Derby after his second-straight win at Caulfield.

The three-year-old son of Reliable Man defeated Mr Quickie at 1600 metres last start and on Saturday accounted for older rivals at 2000m, a victory that now has O'Brien growing in confidence that he could cross the border and be tested at Group 1 level.

The South Australian Derby is on in three weeks and if Grinzinger Star is to head to Morphettville, he will be doing so on the quick back-up as O'Brien is keen to have another run at Flemington in a fortnight.

"There is a 2000-metre race against his own age group in two weeks at Flemington and that could be a nice platform for the South Australian Derby if we feel he is up to the challenge," O'Brien said.

"He is the type of horse who I believe would suit the back-up, he comes in yard looking like he is first-up every race, he carries condition so running twice in seven days should be no issue."

Damien Oliver was patient early aboard Grinzinger Star and the early speed of the race was solid before the tempo slackened mid-race, allowing the champion jockey to improve with little effort.

Grinzinger Star was poised to strike from the 600m and quickly put the race away at the top of the straight before holding off Divanation and Birth Of Venus.

"He is definitely more seasoned this preparation," O'Brien said.

"He was gelded at the end of his last campaign and he is just developing now in to a nice racehorse."

The race wasn't without incident as apprentice Kayla Crowther was involved in a fall, which she appeared to cause herself.

Riding Latin Beat, Crowther was positioned at the rear of the field and attempted to force a tight run on the fence but ultimately caught the heels of La Belle Jude.

Crowther walked from the incident and returned to the jockeys' room, while Latin Beat also appeared unharmed.

Grinzinger Star was bred by The Oaks Stud, and is from their Group 1 New Zealand Oaks winner, Artistic.

-Racing.com