Two crucial gear changes could hold the key to the outcome of the Listed Darby Munro Stakes at Rosehill on Saturday.

Two of the top four horses in betting - favourite Heart Testa and fourth pick Brave Soul - will both wear blinkers for the first time in the 1200m contest.

Heart Testa's trainer Chris Waller has opted for blinkers after the three-year-old suffered his first defeat last start when he was run down late by Ichihara.

"I just feel he could be a little bit soft at the finish," Waller said.

"The blinkers on will help sharpen him up and he might just find that extra length that he needs."

Heart Testa signalled his promise by winning his first four starts before resuming with a narrow second to Ichihara in the Listed Eskimo Prince Stakes.

While he will have the benefit of race fitness, Ichihara will enjoy a 4kg weight turnaround under the set weights and penalties conditions of the Darby Munro.

Brave Soul brings different formlines to the race having finished third behind Complicate and Ashokan in the Canberra Guineas (1400m) last start.

It was her fourth stakes placing and trainer Joe Pride has fitted blinkers in the hope it can help her break through for a valuable black-type win.

"She gets the blinkers on first time. I think it's going to be an important gear chance," Pride said.

"She's worked really well in them and she's finally drawn a good barrier. She will run a cheeky race."