The tough Randwick mile can make or break a horse's chances.

Trainer Matthew Smith is hoping the combination of a heavy track and the famed circuit can benefit Zayam in the Shoot Out Mile at Randwick on Saturday.

The former French galloper's past two wins have been at 1800 and 2000 metres.

"He's probably better over a bit further," Smith said.

The Randwick track was downgraded to heavy on Thursday morning after more than 25mm of rain fell in Sydney and the wet weather is forecast to continue up to Saturday.

While bookmakers rate him as a $26 chance, Smith said a wide barrier draw and a light weight could help Zayam cause an upset in what would be a tough slog.

"He's going well and a mile at Randwick might suit him on a wet track," Smith said.

Zayam finished eighth of 10 runners when he resumed at Rosehill over 1500m last month.

But Smith was pleased with the effort of Zayam to finish less than three lengths off the winner Himalaya Dream, one of his opponents on Saturday.

Now second up - where Zayam has two wins from three starts - Smith believes he has the horse ready to run well again.

But he might not be the only horse who benefits from a tough 1600m, with $3.50 favourite Sebrina stepping back in distance from 2000m.

The Bjorn Baker-trained Sebrina won over 1500 metres on a heavy Rosehill track on June 4 before running second to Foreign Prince over 2000m two weeks later.

Zayam's stablemate Frill Seeking will have her first start at 1400m in a fillies and mares benchmark race on Saturday.

Smith said it had been a frustrating campaign for the five-year-old.

Frill Seeking kicked off her preparation with a luckless run in the Listed Bright Shadow at Doomben which was won by the Smith-trained Palazzo Pubblico.

Following that run, Frill Seeking raced twice at Rosehill without success.

"Nothing seems to have gone right so far," Smith said.

"She's drawn well and she'll race up on the pace.

"She looks like she'll run 1400 metres but we'll find out on Saturday."