Bring on the Cox Plate now.

That was the message from Hugh Bowman, the jockey of Australia's best horse Winx, after the mare made it 12-straight wins and eight at Group One level in the Caulfield Stakes.

The Chris Waller-trained Winx's latest big-race triumph came six days after in-form Hartnell strode to an easy win in the Turnbull Stakes at Flemington.

It sets up a highly anticipated Cox Plate clash at Moonee Valley on October 22 between the two most in-form horses in the country.

"I'm just excited to have a live chance in the race," Hartnell's jockey James McDonald said.

"Obviously we're taking on a champion and champions find something extra special under pressure so Hartnell's going to need to be at his brilliant best to even be competitve there."

Winx is the $1.90 favourite to make it back-to-back Cox Plates with Hartnell at $3.

Black Heart Bart, beaten two lengths by Winx in Saturday's three-horse Caulfield Stakes, is next at $15 along with Hartnell's stablemate Hauraki and Queen Elizabeth Stakes winner Lucia Valentina.

Godolphin's Australian trainer John O'Shea said he was focusing on the preparation of Hartnell and wasn't buying into the hype about the Cox Plate clash.

"It would be an honour to win a Cox Plate for His Highness (Sheikh Mohammed), and as to what is in the race I'm not going to give any focus to," O'Shea said.

"She's a champion mare and you know with Chris and Hughie that she is going to be at her absolute best on Cox Plate day.

"I think with regard to that competition factor, I think that's more for the racing public to get involved in. We're just about getting our own house in order."

While Black Heart Bart was beaten by Winx on Saturday, his jockey Brad Rawiller was proud of his effort after he led the mare for much of the race.

"Winx on the day was too good for us, but bring on the Cox Plate. You never know," Rawiller said.

"We'll need an inch of luck, she'll need an inch of luck, and he's better horse stalking when there's good speed and he's coming off a good tempo.

"She didn't trounce us, so I think we're right in order for the Cox Plate."