Chris Waller hasn't climbed to the top of the Sydney training ranks without backing his own judgment.

He'll be doing that again at Rosehill on Saturday when he starts Moriarty in the Christmas Cup despite a distance query on the import.

"I'm starting to turn into a stubborn old man. I think he'll stay and I'm going to stick by it," Waller said.

Moriarty is third favourite for the 2400m race behind Cantonese and last-start ATC Cup winner Fiumicino.

And contrary to what many might think, Waller believes Moriarty's best chance of success on Saturday will be if the race develops into a real staying battle.

Moriarty has enjoyed good runs in his past three starts between 1900m and 2200m but hasn't picked up and dashed in the straight, finishing in the placings.

Waller says the key will be getting Moriarty to settle in the first half of the race and then "get serious" in the second half.

"If my theory is right I think he needs it to be a true staying test to win," Waller said.

"That might mean not being ridden too pretty."

Cantonese will front up for his 14th start of the campaign but the horse has continued to show trainer Bjorn Baker no signs he's had enough.

Apprentice Jenny Duggan has had plenty of success on Cantonese but cannot use her claim in a Listed race and connections have gone for Jim Cassidy.

"We're probably looking to find a little bit more," Baker said.

"Jenny has ridden him exceptionally well so we may find or we may lose.

"But what it comes down to is Jenny can't claim and Jimmy Cassidy can ride him at the weight and he's a champion rider."

Veteran Fiumicino continues to stave off retirement and co-trainer Michael Hawkes says the nine-year-old has thrived since his ATC Cup win - his first victory since 2009.

"It's amazing what a win does. It just gives them so much more confidence," Hawkes said.

"As long as he puts in a run like he did the other day he'll be hard to beat again."