Marston was due to ride Siberian Rose and Magic Rose for trainer Peter Wiggins in front of 6000 people at Thoroughbred Park on Tuesday.

The 23-year-old was fortunate to have just a broken nose from a sickening fall on Saturday in Tumut, with wet conditions forcing the meeting to be cancelled.

Marston was temporarily knocked unconscious and flown to Canberra Hospital for neck and head scans but has since been released.

She was thrown from her ride Zarababe in the first race of the day after collapsing underneath fellow jockey Jason Devrimol, who fell from his mount first.

"She's lucky she didn't get killed," trainer Wiggins said. "They called the races off so it was pretty bad.

"She's in a neck brace for six weeks with a broken nose and a few things, but she's all right."

James Innes will take over Marston's rides aboard last-start winner Siberian Rose in a Benchmark 65 Handicap (2000m) and Magic Rose in a Maiden Plate (1400m).

With more than 35 years of experience as a trainer and jockey, Wiggins said there was something special about racing on Melbourne Cup day.

"I rode a lot of winners on those days in Canberra and there's nothing better," Wiggins said.

Melbourne Cup day is Canberra Racing's second-biggest meeting of the year behind only Black Opal Stakes Day.

It will also be covered by the TAB after being added to the schedule for the past three years.

Canberra Racing chief executive Peter Stubbs said the increased revenue and exposure for Canberra was a positive.

"It's only been a TAB meeting for the past three years, so that's been a factor in improving the day and revenue because we receive revenue from wagering around the country, which we didn't receive before," Stubbs said.

"There is plenty of atmosphere and entertainment on top of the races, so if anyone wants a genuine racing experience, it's the only place to be.

"From a catering and a bar revenue and admissions, it's certainly a high revenue day for us."

The first of seven races gets underway at 12.42pm, with the last race at 5.40pm.