SA Derby-winning filly gets chance to prove herself against leading Caulfield Cup hopes.

Tony Mcevoy hopes to learn on Saturday whether the spring plans he has in store for Group 1 winner Coco Sun are too ambitious.

This year's South Australian Derby winner will take the next step in her spring campaign in the $750,000 Underwood Stakes at Caulfield.

The Group 1 event will be her toughest test and while the 1800 metres is short of her best, the race includes Fawkner Park and Place Du Carrousel, who are leading contenders for the $5 million Group 1 Caulfield Cup (2400m), which is the race McEvoy is keen to get to with Coco Sun.

"If she's good enough, yes, we'd love to go to the Caulfield Cup and we'll give her the opportunity (to prove she is)," McEvoy, who trains in partnership with his son Calvin, said.

"She's got to step up. She doesn't have to win this race, but she's got to run really well in it, and if she does then she'll go into the Caulfield Cup fourth-up."

The daughter of The Autumn Sun will progress to the Group 1 The Might And Power (2000m) at Caulfield on October 12 if she passes her Underwood Stakes test.

Coco Sun won the 2500m South Australian Derby seven days after finishing third in the Group 1 Australasian Oaks (2000m).

Her only start since those events was a seventh placing over 1400m at Caulfield on August 31, when beaten 2-3/4 lengths by Another Wil, which McEvoy considered a fine cobweb-clearer.

"She's in really good order, she ran fabulously first-up and she'll appreciate getting out to the 1800," McEvoy said.

Coco Sun has the services of Jamie Kah in the Underwood Stakes with the pair to jump from barrier seven in the field that is down to 12 runners following the scratching of Kovalica.