Unbreakable may have booked himself a trip to Adelaide for a Group One race after an all-the-way win at Caulfield.

His victory in the Sky High Mt Dandenong Handicap (1800m) secured a winning treble for the powerful Godolphin stable and jockey Craig Williams after earlier successes with Antelucan and Tarquin.

Sent out the $4 favourite, Unbreakable scored by 2-1/2 lengths from Lightning Bell ($9) with Loyalty Man ($4.40) a half-neck away third.

Unbreakable could now join Tarquin and Etymology, runner-up to Cool Chap in the VRC St Leger at Flemington on Anzac Day, in the Group One South Australian Derby.

David Charles, Melbourne representative for trainer John O'Shea, said both Tarquin and Unbreakable headed to Caulfield on Saturday with a view to Adelaide.

Unbreakable had beaten Tarquin home when they finished second and third respectively behind Bengal Cat in the VOBIS Gold Reef on April 16.

Ever the diplomat, Williams said a decision on which horse he would ride in the Derby was best left to others.

"I never get a pick," Williams said.

"I just leave that up to John, David Charles and my manager.

"They've got three strong chances going into the South Australian Derby if they choose to go that way."

Williams said both Tarquin and Unbreakable would derive a lot of benefit from Saturday's victories after not having ideal runs in their respective races.

He said the South Australian Derby was a completely different race and the three Godolphin horses were coming from different form lines.

"At this stage if they run all three I believe they'll have a very strong three-pronged attack," Williams said.