Preferment has emerged as the most serious threat to the northern hemisphere attack on the Caulfield and Melbourne Cups with his victory in the Turnbull Stakes.

Last year's Chris Waller-trained Victoria Derby winner is now the second favourite behind Japanese horse Fame Game for both Cups after his Group One win on Sunday at Flemington.

But Waller could be swayed from his original plans with the Cox Plate and not the Caulfield Cup a possible Melbourne Cup lead-up after his 2000 metre win.

Ridden by Hugh Bowman, Preferment ($11) scored by a short-head from his stablemate Royal Descent ($6) with 2014 VRC Oaks winner Set Square ($19) three-quarters of a length away third.

"If he had run second to Royal Descent the Caulfield Cup is what we would be doing," Waller said.

"We deserve the right to be arrogant enough to say we could go to the Cox Plate, but the Caulfield Cup is most realistic.

"He's only had the one run over 2500 metres so it would be best going into the Melbourne Cup rock hard fit, not hoping he's going to stay.

"It's a question mark every 3200 metre race and that extra distance does test them."

"I know the Derby doesn't always throw up a good record going towards Melbourne Cups, but this horse is a little bit different as he's been so lightly-raced," Waller said.

Royal Descent's second was the mare's seventh minor place in a Group One event since she won the 2013 Australian Oaks.

"She was there for a long way up that long Flemington straight, so she lost no admirers," Waller said.

Bowman, who combined with the Waller-trained Winx to win Saturday's Epsom Handicap at Randwick, said he thought Preferment was suited by the bigger Flemington track more than he would be at Caulfield or Moonee Valley, the venue of the Cox Plate.

"My gut feeling is he'll be better suited on a galloping track," Bowman said.

"He likes Flemington and he's a more mature unit than he was last year.

"He's a Group One horse and is furnishing into a Group One athlete."

Luke Currie, rider of third-placed Set Square, said last season's VRC Oaks winner was unlucky after being held up for a run at a vital stage.

Ben Melham, who rode fourth-placed Dandino, said the effort was pleasing.

"He just needs to draw a barrier," he said.

James McDonald, rider of Hartnell, who finished sixth, said the Godolphin galloper was back on track, describing the run as fantastic.