Gregson's main target at the rescheduled Tokyo Olympics - assuming it goes ahead - remains the 3000m steeplechase.

But she's also keen to earn the chance to double up in Tokyo.

Ellie Pashley is the only runner in the women's field to have already bettered the tough qualifying mark of 31 minutes 25 seconds - achieved when she finished a creditable 13th at the world titles in Doha in late 2019.

But Pashley's main Tokyo focus is the marathon.

The field for the women's Zatopek:10 at Box Hill athletics track also includes gun Australian Sinead Diver, Canadian Andrea Seccafien and impressive local youngsters Isobel Batt-Doyle and Rose Davies.

Bideau can see the race record of 31:26.34 set by Susie Power in 2001 coming under serious threat.

"We could possibly see three or four girls in the range of that time and it would be amazing if we could get three under 31:25," said Bideau.

"I reckon we are certainly going to see four or five of them run under 32 minutes which has never happened before."

Gregson's winning time in the most recent edition of the Zatopek:10 in late 2019 was 32:47.83, but Bideau believes she has the capacity to run much faster in a stronger field.

"Gen is a greedy bugger, she wants to run in two events in the Olympics," he said.

"She'll be hard to beat because she's a great competitor.

"She's got to run over 30 seconds faster (then her PB) and Diver has run around 31:25.

"But I would probably still make Gen the favourite because if she's near the lead with a kilometre to go most likely she'll win.

"She's hard to beat from there because they will have to get rid of her."

The men's 10,000m national championships is lacking in star power due to the absence of Stewart McSweyn and Patrick Tiernan, both of whom have already bettered the Olympic qualifying standard.

The field includes Jack Rayner, Brett Robinson and Dave McNeill.

Australian Associated Press