Dwayne Dunn has waited 15 months to ride Gregers in Saturday's Group One Goodwood at Morphettville.

Dunn won on Gregers when the filly made a successful debut at Moonee Valley in February last year before steering her into fourth at her next start in the Group One Blue Diamond Stakes.

But circumstances kept Dunn out of the running to ride the David Hayes-trained Gregers again with Chad Schofield, Kayla Nisbet, Michael Rodd and Craig Williams partnering the three-year-old in her subsequent runs.

Williams rode Gregers to third in the Group One Robert Sangster Classic last time out before heading to Japan for two months, leaving the mount open for Dunn in Adelaide's premier sprint.

Dunn says a fitter Gregers can improve on her Sangster Classic performance in Saturday's $500,000 contest.

"David said he took her into the Sangster a little fresher thinking that was the way to have her," Dunn said.

"She probably lacked a little bit of fitness so she'll improve from that and dropping a kilo in weight will only help her."

Dunn said barrier five was perfect for Gregers and TAB punters agree, backing the three-year-old from $11 into $10 on Friday.

Darley galloper Sessions and local hope Essay Raider have also firmed from $11 into $10 while the Group Two Sportingbet Stakes winner Miracles Of Life shortened from $8 to $7 at her final start before she is sold at public auction.

Barrier five could be significant for Dunn, who will also ride Gregers' three-quarter sister Girl Guide in the Group Three Proud Miss Stakes (1200m).

Girl Guide has won four of her five starts and booked a shot at stakes company with her strong win at Sandown on April 26.

"She doesn't win by much but she puts them away," Dunn said.

"She's going so well that you have got to have a throw at the stumps in a race like this."