There's a grey area in the data Chris Waller keeps on his racehorses.

Her name is Catkins.

For a trainer who likes to deal in the black and white of the statistics he meticulously compiles to monitor the wellbeing of his stable, Waller is making an exception for the grey-coloured darling of Sydney racing.

"It seems she just does things most normal horses can't do. She won first-up 10 kilos heavier than her normal racing weight," Waller said.

"They don't normally win when they are like that. They normally need to get back to their racing weight.

"Hence the reason why I was a bit guarded first-up."

Catkins will have to defy the science behind Waller's data for the second time in as many starts when she goes out as an odds-on favourite in the $400,000 Golden Pendant at Rosehill.

When narrowly beaten in the 2014 Golden Pendant, Catkins weighed in at 502kg and she will tip the scales at 523kg on Saturday

"We've got a 20-kilo heavier horse and normally that doesn't augur well," he said.

"But she's got a tremendous heart. A trainer can't ask for much more than that."

Catkins has made an art form of putting herself into the race with a minimum of fuss and it has served her well in 16 wins for more than $2 million prize money.

But Waller said the nature of her first-up win in the Sheraco Stakes reflected her trackwork as she was outpaced from the barrier and had to muster a finishing sprint from midfield for one of the few times in her career.

"She hadn't been showing as much spark on the track and raced accordingly," he said.

"She raced back in the field and still picked them up."

Arabian Gold just had Catkins' measure in last year's Golden Pendant and she is tipped to make it an all-grey finish once again at her second start for new trainer Gai Waterhouse.

There was merit in Arabian Gold's Tramway Stakes fourth after she raced at the girth of the leader and winner Hooked and she goes around against her own sex for the first time since a midfield placing in the Coolmore Classic.

Catkins will be the second horse from Waller's team to run as an odds-on favourite at Rosehill.

Three-year-old Press Statement dominates early betting on the Stan Fox Stakes as he tries to confirm his rating as one of the favourites for the Caulfield Guineas.