All eyes are on one variable never before seen at a Melbourne Cup Carnival: the empty trackside.

Equine science expert Dr Andrew McLean told Deborah Knight it’s hard to predict how the much quieter atmosphere will affect the horses.

“These horses are very tolerant animals … and they’ve had an upbringing in their racing careers from very small crowds right through to the big time.

“It might have some slight advantage for some horses.

“It could be anyone’s game.”

However, the lack of crowd noise is as much an unknown variable for the jockeys as it is the horses.

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