Edward Cummings has a surname famous in racing circles but it was a different kind of family knowledge that led him to buy $2 million Inglis Millennium hopeful Sunborn

Having just dissolved his training partnership with father Anthony, Cummings was taking his first steps as a trainer in his own right when he came across Sunborn at last year's Inglis Classic sale.

Not only did he like the Casino Prince filly on type and temperament, he had previously trained her half-sister, city winner Making Whoopee.

"She looked like a strong, well balanced filly, a really sensible horse," Cummings said.

"She is a very good moving horse and the added benefit I had is I had trained her half-sister by High Chaparral with my father so I knew a little bit about the family.

"I was around at the stable when Dad had (her dam) Honeymoon Cruise in work and she was always very talented.

"I suppose that background knowledge helped me bid confidently."

Almost 12 months later and Sunborn will line up in the Inglis Millennium (1100m) at Warwick Farm on Saturday, a race markets indicate is at the mercy of reigning Golden Slipper favourite and odds-on elect Cellsabeel.

Encountabull is the only runner given a serious chance to threaten the Ciaron Maher and David Eustace-trained filly but Sunborn's form through that colt is strong.

After a debut win at Newcastle, Sunborn was doing her best work late for fifth to Wild Ruler in the Inglis Nursery (1000m) at Randwick in December, just over 1-1/2 lengths behind runner-up Encountabull.

Since then she has been given a short break and another quiet barrier trial and at $71, Cummings believes Sunborn can be competitive.

"She put the writing on the wall early with some nice trials and then won on debut and I thought her run was very good in the Nursery, albeit it unlucky," Cummings said.

"I think she has gone on from that race and after a short let-up, she is there to run well on Saturday."

With heavy rain forecast for Sydney, stewards have flagged the possibility of shifting the Inglis Millennium meeting to Rosehill if Warwick Farm is unsafe for racing.

Either way, the race is likely to be run on a heavy track which will be uncharted territory for most of the 14 runners, including Sunborn.

"Every indication she has given is she's pretty unflappable so I'd expect her to handle it," Cummings said.

"That being said, it's impossible to tell, particularly at Warwick Farm on a heavy 10."

Cellsabeel is the only youngster with exposure to a heavy track having scored a six-length win in similar conditions at Randwick last month.