It had been suggested Princess Tiffany was tired at the end of a long campaign after her shock defeat in her heat of the Victorian series earlier this month.
Purdon, who trains the 3yr-old with Natalie Rasmussen, put the unusually lacklustre performance down to the testing wet conditions.
"Her first-up run was way below par for her," he said.
"We thought it may have been the track that she didn't handle, but she bounced back to her old self last Saturday."
The All Stars filly quickly rebounded with a brilliant win in her semifinal at Ballarat last weekend, which combined with her barrier 3 draw, will have her start a heavy favourite in the group 1 series final for 3yr-old fillies at Melton tomorrow night.
Purdon dismissed any suggestion that Princess Tiffany was feeling the effects of a long season before her attempt to win consecutive Australasian Breeders Crown finals.
"I think she has handled the season well," the trainer said.
"In the case of Jesse Duke, he has got tired.
"He was up early in the season.
"But, I don't think this filly is. She punched through from the second row last week and did plenty of work early.
"And she ran a slick last half [800m]."
All Stars stable travelling foreman Matthew Bowden has delivered positive reports about Princess Tiffany to Purdon this week.
Their biggest challenge has been variable Victorian weather.
Princess Tiffany was rated a $1.18 favourite with the Australian TAB yesterday.
Harness Jewels winner Jesse Duke is unlikely to race in Australasia again.
The Purdon and Rasmussen-trained 3yr-old, who has been bought by North American owners, failed to qualify for tomorrow's finals.
