Gerald Ryan concedes the 1200 metres of the Missile Stakes will be too short for Australian Derby runner-up Harper's Choice but the Group Two race will still give the trainer some idea where to head this spring.

Although Harper's Choice led for most of the 2400 metres of the Derby before being run down by Jon Snow, Ryan is not convinced he is a true stayer and will get more of a guide from Saturday's sprint at Randwick.

"It's a good place to kick off with him," Ryan said.

"The plan is to run him over 1200 then 1400 metres and decide after that whether he could be an Epsom horse.

"I'm not convinced he is a stayer but we'll keep an open mind until we see him race."

Jason Collett retains the ride on Harper's Choice, one of 13 nominations taken on Monday headed by the Kris Lees-trained triple Group One winner Le Romain who is the TAB's early $2.30 favourite.

Tattersall's Tiara winner Tycoon Tara, who won the Missile a year ago, is the $5 second-elect ahead of Jungle Edge ($6).

Trained at Cranbourne by Mick Bell, wet-track specialist Jungle Edge enjoyed a fruitful autumn with two Group Three wins and three Group One placings.

After rain in Sydney on Monday, more is expected on Thursday which will also suit The Monstar, winner of the June Stakes and runner-up in the Ramornie Handicap.

While Harper's Choice has already shown his class at the highest level, stablemate Tango Rain hasn't yet had the chance but Ryan hopes he can start the build-up in a benchmark 80 race on Saturday's program.

The winner of two of his four starts, Tango Rain has not raced since last September but showed his fitness with a recent barrier trial win.

"He had a virus so he didn't race in the autumn," Ryan said.

"We've got a big opinion of him but because he hasn't raced for so long he has to get a few ratings points before we make any plans."