Many mares her age are nearing retirement but Group Two Dane Ripper Stakes contender Platinum Rocker is a long way from the breeding barn.

Platinum Rocker is rising seven but has only raced 15 times after a succession of issues delayed her debut until she was a four-year-old.

"She always possessed the ability but lacked the strength to do it because of feet and knee trouble but that didn't worry me because I always knew she had the ability," trainer Simon Miller said.

"Now we are reaping the rewards because she is sound and racing really well."

Miller set Platinum Rocker for the Tatts' Tiara in Brisbane after she finished third in her first Group One appearance in the Railway Stakes in Perth last year.

The trainer briefly flirted with running Platinum Rocker in the Stradbroke Handicap but successive thirds behind boom filly Srikandi persuaded him to race his charge against her own sex.

"Her main mission is the Tatts' Tiara because that is set weights," Miller said.

"She just needed the run the other day and it topped her off nicely but I thought it would be best to go back to the fillies and mares race."

Miller initially thought Platinum Rocker would complete her Tatts' Tiara preparation with a solid placing behind the Chris Waller-trained Catkins in the Dane Ripper Stakes.

However, the pre-post favourite was a surprise withdrawal from the Dane Ripper Stakes on Friday morning.

"I got a text telling me Catkins was out of the race and that's going to open the race right up," Miller said.

Miller said Platinum Rocker's run in the Group Three Glenlogan Park Stakes ensured she would be fit enough to win the Dane Ripper Stakes but tactics would play a big part.

The Perth trainer said drawing barrier two would give regular rider Peter Knuckey plenty of options to position Platinum Rocker perfectly.

Knuckey gave up a likely full book of rides at Saturday's Belmont meeting to travel across the country just to continue his association with Platinum Rocker at Eagle Farm.

"He (Knuckey) has won eight on her so he loves her and he keeps coming across for that one ride," Miller said.

Miller said Platinum Rocker would return to Perth after her Brisbane commitments to spell before preparing for another shot at the Railway Stakes in late November.