Savvy Nature joined Complacent as Derby favourite with victory in last Saturday's Group Two Vase (2040m) at Moonee Valley, a race Snowden decided he didn't need to run Complacent in.
O'Shea says the barrier draw will play a big part in Savvy Nature's chances. "I think that if we are going to win, the barriers are going to be vital.
"The two times we've met him, we've had to give him a big start. We just need to draw a gate where we can sort of get within striking distance in the run so that we are not setting ourself too great a task."
The Randwick-based trainer hopes to draw inside barrier eight.
He expects the seven-day back-up, a bigger track and the experience Savvy Nature gained from his first Melbourne start to help.
O'Shea is also confident the son of Savabeel can run out the Derby trip.
Meanwhile, Voleuse De Couers impressed pundits when working at speed at the Werribee quarantine station yesterday.
As a result, the European mare shortened in Melbourne Cup markets from 14-1 to 12-1.
Voleuse De Couers is a recent addition to Mike Moroney's stable, having previously been trained by Dermott Weld in Ireland.
She scored easily in the Irish St Leger before being transported to Melbourne and will be ridden by James McDonald next Tuesday.
The Melbourne Cup distance should be a walk in the park for one of her rivals, Simenon, the Irish hurdler-turned-stayer who had a familiarisation excursion at Flemington yesterday.
Simenon went as far as being marched around the parade ring before trotting along the raceway lined with roses and on to the course proper before completing two laps in a solid workout.
Emmet Mullins, nephew of trainer Willie Mullins, said they wanted Simenon to have a stretch and get used to the surroundings.
"I know it's nothing like coming up through that tunnel on raceday, but at least he's been here now and he's done it," Mullins said.
Simenon is a dyed-in-the-wool stayer who regularly runs in races beyond 4000m in Britain.
Last year he won the Queen Alexandra Stakes at Royal Ascot over 4369m and in June he failed by a neck to beat the Queen's horse Estimate in the prestigious Gold Cup at Royal Ascot over 4023m.
Locally, Simenon showed what he is capable of with a strong third in the Herbert Power Stakes (2400m) at Caulfield three weeks ago finishing just over a length behind Sea Moon.
"It's the first time he's run a mile and a half while we've trained him - we always knew he had some speed but at least he went out and showed everyone."
- AAP