One start on Victoria's provincial circuit has been enough to convince trainer Tony Noonan to aim higher with Magnus Opus.

On the strength of a Seymour 1100-metre win in late November, Magnus Opus will take his place in the $150,000 VOBIS Gold Carat (1200m) at Caulfield.

Noonan has targeted Saturday's race in the belief Magnus Opus wants more ground.

"He's a promising horse but he still has a lot to learn," said Noonan.

"He's a long way from reaching what I think is his potential.

"He may get over a little bit more ground so we made the decision not to run him again before Saturday's race."

By former top sprinter Magnus, Magnus Opus is out of the unraced Bel Esprit mare McCune and was bought for $35,000 from the Inglis Premier Yearling Sale.

Noonan said if Magnus Opus, to be ridden by his son Jake, can produce a strong performance then he will have one more race before a let-up.

"He had a wind operation as a two-year-old so I would like to give him a break after three runs just to let him develop a little further."

Magnus Opus is a $21 chance behind the Darren Weir-trained favourite Trust In A Gust at $2.40.

Trust In A Gust stands out as the form runner with four wins and two placings in seven career starts.

At his most recent start on November 24, Trust In A Gust ploughed the mud on Ballarat Cup day to win the Eureka Stockade.

Noonan, meanwhile, also has four-year-old gelding Cast Iron, formerly trained by Greg Eurell, running for the first time for his stable in the Tim Sando Handicap (1200m).

Cast Iron's only win in a nine-start career was at his second outing at Stony Creek last January.

"I trained his mother and his half-sister so I have had a little success with the family," said Noonan.

"He has been disappointing to date - we're experimenting at this stage and hopefully we can get him to improve."