The opening day of the Melbourne Cup carnival brings about a change of attitude in the jockeys.

There's little banter between the riders who are focused on their mounts in the nine stakes races, four at Group One level.

Senior jockey Dwayne Dunn notices the change in the jockeys room each year.

"The game changes now," Dunn said.

"For us as jockeys we find it more draining, not so much physically, but mentally.

"On a normal Saturday you might have a good ride that you are really motivated for but every race on Saturday you have to be on your game right from the start."

Dunn describes Victoria Derby day as Australia's best day of racing.

He said earlier in the carnival there might only be three or four chances per race, but come Saturday that rises to sometimes seven or eight.

With rides in the four Group One features Dunn is looking forward to Star Turn in the Coolmore Stud Stakes for three-year-olds which he said could be the race of the carnival.

"There's six or seven serious horses in there," Dunn said.

"Maybe some of them might actually dodge it and go to the Darley now that Chautauqua's not going there."

Dunn said Star Turn had a jump-out at Flemington last Friday and was comfortably held, but pointed out the colt was accounted before winning the Schillaci Stakes at Caulfield.

"Without his blinkers on he only does what he has to do," Dunn said.

"When he's got the blinkers on, he's a different horse."

He's Our Rokkii, who Dunn partnered to win the Toorak Handicap at Caulfield, is his mount in the Cantala Stakes (1600m).

Dunn said He's Our Rokki had been well-placed in his three runs this campaign, culminating in his Group One Toorak success.

"He's kept stepping up to the plate everytime we've raised the bar but this is by far his toughest test," Dunn said.

Dunn has chosen the Tony McEvoy-trained Don't Doubt Mamma over Star Turn's Hawkes Racing-trained Euro Angel in the Myer Classic.

"The question mark with her is the mile and she'll need to draw really well to be closer in the run and relax," Dunn said.

"It was a tough decision to get off Euro Angel, but Don't Doubt Mamma has been good to me."

Dunn said he would partner either Inference or Swear in the the Victoria Derby for Hawkes Racing.