Owners Lloyd and Nick Williams could not have wished for a better Australian debut from Irish import Crocodile Rock.

The four-year-old Galileo gelding made a one-act affair of the Le Pine Funerals Handicap at Sandown on Wednesday under Katelyn Mallyon.

Taking the lead down the back straight, Crocodile Rock was allowed to stride coming down the hill and early in the straight the gelding held an eight-length advantage.

Mallyon took hold of the $4.80 favourite over the final 150m of the 2100m contest before he scored by 2-3/4 lengths.

Nick Williams said Crocodile Rock had some minor issues in his younger days but had won his maiden well in Ireland before coming to Australia.

"We'll see how he pulls up and we'll see if we can find another race for him," Williams said.

"There's a long way to go to see what sort of grade he's going to make but he couldn't have been any more impressive.

"It's hard to say where he might get to but we're hopeful that he can get through his grades and be a nice stayer."

Kerrin McEvoy rode the Williams-owned The United States and Gallante to Group One wins during the Sydney autumn carnival, while Mallyon has been aboard the Williams' recent winners in Melbourne and Adelaide.

Mallyon and Melbourne Cup-winning jockey Michelle Payne have been going to the Williams' training centre at Mount Macedon to ride work and have been rewarded with race rides.

"They do a great job on these horses," Williams said.

"They've both got terrific hands and both have been riding a bit of work for us, so we're happy to give them rides in races."