Chris Waller is accustomed to preparing the headline horses for Australia's biggest races.

At Flemington on Saturday, he will have to settle for the role of underdog.

While his Black Caviar Lightning runners Delectation and Japonisme are Group One winners, even Waller concedes they are at the mercy of Australia's benchmark sprinter Chautauqua and his heir apparent Exosphere.

"I'm just hoping Chautauqua's not quite as forward as they'd like because if he's the fittest horse in the race he's extremely hard to beat," Waller said.

"And I'm hoping Exosphere is not as effective down the straight as he is on bend because on a bend he's lethal."

Exosphere held market sway early in the week but by Thursday was sharing top billing with Chautauqua at $2.50.

James McDonald has bypassed the Silver Slipper meeting in Sydney to stick with Exosphere who failed at his only other attempt down the Flemington straight when a well-beaten fourth to Japonisme in the Coolmore Stud Stakes last spring.

He gets the chance to prove that run an anomaly and his trainer John O'Shea is more concerned by the giant-striding colt's rails draw than any aversion to straight racing.

"It's not a good draw for him," O'Shea said.

Waller has no such queries with Japonisme or Delectation who both posted their biggest career wins over the Flemington straight course.

However, the 1000m of the Lightning does present a challenge.

"Delectation has got weight-for-age form on the board around Chautauqua and Terravista but he's a better 1200-metre horse," Waller said.

"Japonisme has proven he's a consistent horse and he's an up-and-comer that would be slightly better suited to the 1000 than Delectation.

"With that said, they will both be better horses in the Newmarket having had a first-up run on Saturday."

Chautauqua, a superior fresh performer, will be striving to end a frustrating run of seconds in Flemington Group One races.

A multiple stakes winner down the straight, Chautauqua has been runner-up in the past two editions of the Darley Classic and last year's Newmarket Handicap with his two elite victories recorded at Moonee Valley and Randwick.

Sydney speedster Terravista shares the second line of betting with Delectation at $8 while Japonisme is a $9 chance.

Kinglike ($23) and Va Pensiero ($61) make up the Group One field.