Two Golden Slipper lead-ups will be run at Rosehill on Saturday but trainer Michael Hawkes is certain only one can reshape betting on the $3.5 million race.

Hawkes Racing's unbeaten filly Mossfun clashes with Darley's undefeated star Earthquake in the Reisling Stakes in a Slipper qualifier made even more intriguing because of the barrier draw.

Mossfun will have to overcome the widest gate in a field reduced to nine runners on Friday because of the scratching of Oakleigh Girl.

Earthquake has drawn one stall inside Mossfun.

Besides both fillies shooting for four-straight wins and trying to keep an unblemished record, Hawkes says the Reisling will have the most bearing on Golden Slipper markets.

"Whoever wins this race will end up favourite for the Slipper," he said.

Earthquake is odds-on to make a winning return to Sydney racing in the Reisling with Mossfun a clear second pick.

The betting is a mirror image of their standing in latest Golden Slipper trade with Earthquake at $2.80 and Mossfun on the second line at $8.

Mossfun's most dominant win was her most recent when she posted a four-length victory in the Silver Slipper Stakes at Rosehill on March 1.

"She has done everything right and she is there to win," Hawkes said.

Melbourne jockey Craig Williams will replace Tommy Berry on Todman Stakes favourite Unencumbered.

Berry's twin brother Nathan has ridden Unencumbered to five victories, including this year's Magic Millions.

But with Nathan in hospital fighting viral encephalitis, Tommy was booked to ride the colt until he decided to fly to Singapore on Friday to be with his brother.