A track gallop on Tuesday will determine the immediate path for lightly raced stayer Oncidium Ruler.

Trainer Mick Kent says the three-year-old will contest either the Listed VRC St Leger (2800m) at Flemington on Saturday or the Group One South Australian Derby (2500m) at Morphettville on May 9.

"It's one or the other but it won't be both," Kent said.

"If he pleases me on Tuesday we'll run him at Flemington, otherwise we'll save him for the South Australian Derby."

Oncidium Ruler is one of 17 nominations for the St Leger. Sydney trainers John Thompson and Bjorn Baker have entered General Zabeel and Zatopaz respectively while New Zealand training partners Trent Busuttin and Natalie Young have nominated Gifted Lad.

Oncidium Ruler has only had three starts with Kent saying the gelding is still immature but with the potential to develop into a more than handy stayer.

After a debut third in a 1600m maiden at Ballarat in early March, Oncidium Ruler stepped up to win a 2400m maiden at Geelong.

He then headed to Flemington for the Galilee Series Final on April 11, finishing a close second to Manapine over 2500m.

The Nigel Blackiston-trained Manapine is a notable absentee from the St Leger and will be aimed at the SA Derby.

Kent said the four weeks between Oncidium Ruler's Flemington placing and the SA Derby was ideal but the prospect of a weaker race on his own doorstep was enticing.

"I know he's really immature so it's a real balancing act for me," Kent said.

"I would want to be confident of winning or getting the fat end of the prize money to do it to him because he is really not ready.

"He's eating well and he's done well since his last run.

"He hasn't done any fast work since but he will on Tuesday and if he handles that and pulls up well then we'll go ahead to Flemington."

All I Survey (third) and General James (fourth) in the Galilee Series Final are among nominations as is Sunday's Seymour maiden winner Cuban Fighter who finished ninth to Preferment in the Victoria Derby in the spring.

Kent also has Epingle nominated in two feature races at the Gold Coast on Saturday.

She has been entered in the Group Two Hollindale Stakes (1800m) to take on the likes of Foreteller, Green Moon, Hawkspur and Pornichet and also in the Chairman's Handicap over 2200 metres.