First Seal's trainer John Thompson prefers not to dwell on the mare's injuries which have interrupted her career since she regularly got the better of Winx.

In their three-year-old season, First Seal had the better of Winx four times including the 2014 Group One Flight Stakes.

That remains her only Group One win to date with Winx now up to No.9 with her second Cox Plate win on Saturday.

First Seal can peg the differential back by one in Saturday's Myer Classic at Flemington with the five-year-old preparing with a stylish work-out at the track on Tuesday.

"She's a special mare to us and it means a lot to see her getting back to something like her best," Thompson said.

"She has had a couple of serious injuries but she is now sound and happy and if she is at her best, she can win on Saturday.

"I'm confident she's getting back there and I've been very happy with her all preparation."

After a disappointing return when fifth in the Golden Pendant at Rosehill on September 24, First Seal showed her quality at her first Melbourne start when she won the Group Two Tristarc Stakes at Caulfield last Saturday week.

That win has earned her $4.40 favouritism for the Myer Classic (1600m) for fillies and mares ahead of Wednesday's declaration of the final field.

Thompson will also saddle up Zanbagh who he admits cannot beat First Seal, all things being equal.

"I can't see her beating First Seal but if we happened to get some rain, that brings Zanbagh into it," he said.

"I also have a lot of respect for Tony McEvoy's horse."'

The McEvoy-trained Don't Doubt Mamma is the TAB's $4.80 second favourite after her two recent Group Two wins.