The stage is set for an epic Cox Plate at Moonee Valley with champion mare Winx and in-form Hartnell headlining a field of 10 for the country's best weight-for-age race.

With connections able to choose their own barriers on Tuesday, Winx's part-owner Peter Tighe was second cab off the rank and selected three with Happy Clapper already in four.

Winx immediately tightened from $2 to $1.90 to extend her winning streak to 13 and become the fourth mare, and first since Sunline in 1999 and 2000, to win two Cox Plates.

Saturday's $3 million race is being billed as a showdown between Winx and Hartnell who has recorded big-margin wins in his past three starts and is the only other runner under double figures at $3.

Winx's jockey Hugh Bowman is happy with barrier three and will study where he thinks his rivals will be and how the race will be run.

"For me it's about keeping it simple and having the horse comfortable. And if that's the case, she'll be very hard to beat," Bowman said.

Bowman said from the draw he won't be committed to making a decision he doesn't want to make.

"There's all sorts of scenarios that will play through my mind over the next few days," he said.

"But ultimately what I'd love to see, with all due respect to all the other runners, I'd love to see Hartnell and Winx both get a fair run, a run that suits them, and I think we'll see a very, very good horse race. And it's a privilege to be a part of it."

Winx turned in sparkling piece of work at Moonee Valley on Saturday before a comfortable gallop there on Tuesday.

"I'm certainly very excited about the way she's going," Bowman said.

Hartnell's jockey James McDonald is looking forward to the clash.

Winx has beaten the John O'Shea-trained Hartnell in their three meetings but McDonald says Hartnell is going better now.

"John's got him ticking along beautifully. Bring on Saturday and hopefully we get a bit of luck during the run and he'll be thereabouts when the whips are cracking," McDonald said.

McDonald would like Hartnell, who has gate seven, to be in front of Winx in running.

"We're taking on a champion and they find something when they need to find something. And I'm sure she will," he said.

"But I'm looking forward to the clash because my horse can't go any better."

McDonald said the other runners also commanded respect including stablemate Hauraki and French horse Vadamos.

There has been plenty of talk about where the speed might come from and Awesome Rock's co-trainer Troy Corstens has declared the stable's hand.

"We're going to go forward," Corstens said.

"If Vadamos doesn't want to lead, we will be. If (Vadamos) wants to go stupid we'll probably let him go and just sit in behind him, but we're going to be very positive and if we can get a nice lead we'll be doing it."