Chris Waller has the utmost respect for BMW winner Hartnell but is relying on Melbourne Cup form as the best guide to the Sydney Cup.

The two races are the only Group One races left in Australia over the gruelling 3200 metres.

Waller sends out two runners - Grand Marshal who is making his Group One debut - and tough stayer Who Shot Thebarman, third in the 2014 Melbourne Cup in his first preparation for Sydney's premier trainer.

The Melbourne Cup winner Protectionist and three time runner-up Red Cadeaux are also in the race although the latter may be diverted to the Queen Elizabeth Stakes (2000m).

"There is no better form than the Melbourne Cup for a two-mile race," Waller said.

"Who Shot Thebarman has really matured. He is a much stronger horse and has had the perfect preparation.

"He was very good in the BMW and I have a lot of respect for Hartnell.

"He is the horse to beat and is dropping a lot in weight from weight-for-age.

"And Protectionist gets back up to two miles.

"It's great to the first three in the Melbourne Cup in the race. Every Melbourne Cup placegetter should be in it.

"It's the best Sydney Cup for some years."

Hartnell is the $2.70 favourite ahead of Who Shot Thebarman at $4.40 and Protectionist at $6.

Blake Shinn has the ride on Who Shot Thebarman while Jim Cassidy will be aboard Grand Marshal, third in Monday's Chairman's Handicap behind Tremec and Sir John Hawkwood, neither of whom are backing up in the Cup.

"Grand Marshal has earned his place and won over 2800 metres at Flemington on Cup day in November," Waller said.

Who Shot Thebarman already has a Group One win over the distance in last year's Auckland Cup which prompted his owners to send him to Australia to test his credentials.