Sydney traffic cost Melbourne-based jockey Daniel Moor a Group Three win after he was forced to give up the ride on Epona Stakes winner Vergara.

James McDonald picked up the mount after Moor's traffic woes meant he was not at Rosehill in time to ride the Anthony Cummings-trained mare in the first race on Golden Slipper day.

Vergara, a $12 chance, led all the way to hold off a spirited challenge from $3.80 favourite Heavens Above by a half neck, with Sweet Fire ($7) finishing third.

McDonald was counting his blessings after getting a late call-up.

Cummings said while there was no pain in putting McDonald on Vergara, Moor deserved credit for the placement of the horse.

"Daniel advised us on going to the 1900 metres after her last run and it was his advice as much as any that got us here," Cummings said.

"It's a shame he couldn't take the ride today."

Cummings said Vergara may now tackle a race during the Randwick carnival, before being aimed at the Brisbane winter carnival.

"This will probably be her last racing season," Cummings said.

"She will go through to Brisbane over a similar staying trip and maybe something like the Hollindale Stakes."