The Turnbull Stakes meeting at Flemington shapes as a defining day for a number of spring aspirants.

Saturday's UCI Stakes for three-year-olds is regarded as D-day for a number of potential stayers aimed at the Victoria Derby (2500m) at Flemington in four weeks.

Just as they did 12 months ago, partners Trent Busuttin and Natalie Young will saddle three runners in Saturday's 1800m contest.

They scored last year with Main Stage, Johnny Vinko finished third and Padraig was down the track.

Main Stage and Johnny Vinko went on to the Derby, joined by runner-up Sully.

Cosmic City, Louie The Legend and Savvy Oak carry the hopes of the stable in Saturday's race.

Busuttin said Cosmic City reminds him of Main Stage and goes into Saturday's race having won a Sale maiden at his last start.

"On face value he's won a maiden over 1600 metres and needs to step up but I put him in a similar category to Main Stage," Busuttin said.

"This time last year he (Main Stage) won a Kilmore maiden very unconvincingly but he stepped up to win this race.

"This horse, the further he goes, the better he'll be and if he could run in the top five or six he'll show us he's on track to get the 2500 (metres) of the Derby."

Savvy Oak has drawn the widest barrier on Saturday and will have Hugh Bowman in the saddle with Busuttin saying the plan is to ride him conservatively.

"I think you'll see a big race from him on Saturday," Busuttin said.

The third of the trio Louie The Legend tries hard in his races.

"The races aren't getting any easier but he's done nothing wrong so we might as well have a crack," Busuttin said.