Nigel Blackiston believes rain in Melbourne could be a bonus as he prepares to start three-year-old Mossara Lad for the first time at Sandown.

Mossara Lad has shown the Flemington trainer enough in his jump-outs to be convinced he is capable of figuring on debut in Wednesday's Appelles Maiden Plate (1200m).

"He's had two or three very nice trials and he's a nice style of a horse," Blackiston said.

"Obviously he's got a lot to learn and is still green and immature, but on what he's shown me so far I'm very pleased with him."

The Sandown track was downgraded into the soft range of Tuesday after 16mm of rain in the past 24 hours.

But with Mossara Son being by Mossman the trainer was not fazed.

"He seems to be quite professional and begins well in his trials," Blackiston said.

"The Mossmans do seem to like a bit of moisture in the track so that might be to his favour and I'm expecting him to go there and run a big race."

Blackiston has called on Dwayne Dunn to partner Mossara Lad.

If Mossara Lad can score it would snap a recent run of outs in Melbourne metropolitan racing for the top jockey.

Dunn's most recent city winner in Melbourne came in November but he still sits only one win behind premiership leader Damien Oliver having ridden 22 city winners this season.

Trainer John Sadler had been planning to start both Gallant Harmony and last-start Cranbourne winner Marli Magic at the midweek meeting if the track conditions suited but they were both scratched on Tuesday afternoon.

Blackiston prepared Heez Notorious to win at last Wednesday's Sandown meeting.

The six-year-old gelding will be among the trainer's representatives at Flemington on Saturday, taking his place in a 2000-metre open handicap with visiting apprentice Kieran Shoemark retaining the ride.

Shoemark rode a winning double last Wednesday.

He returns at Sandown from a seven-meeting suspension and has four rides.