Stephen Baster admits he flick-passed a decision on which stablemate to ride at Caulfield to co-trainer Troy Corstens.

With Corstens and his father and training partner Leon having two runners, Modern Wonder and Conscious, in the Group Three Winslow Group Stakes on Saturday, Baster was told he could ride whichever one he wanted.

Having ridden the pair in work and in jump-outs at Flemington he was unable to split the pair.

"They gave it (the decision) to me to make," Baster said.

"I couldn't decide because I've ridden them in trials and I reckon they've gone as good as each other.

"I was just praying they wouldn't run in the same race, but unfortunately they are.

"I just said to Troy `you do what suits the stable the best and I'm happy with either horse'."

Baster will ride Conscious while Daniel Moor has been booked for Modern Wonder.

Modern Wonder won on debut in Adelaide under Baster in April with Conscious running a debut second behind the smart Weatherly at Flemington in February.

Baster thinks that on their work, and jump-outs, they will be competitive on Saturday.

"They're both good fillies and I'm sure they'll win their share of races," Baster said.

"All the fillies at this time of year everyone wants to stretch them out to the Thousand Guineas, but these two are definitely quick.

"Whether they get there I don't know, but obviously you've got to try.

"The one I'm riding scoots along and I would say she'll be in front of the other one."

Baster will be able to keep an eye on Modern Wonder as the pair are drawn next to each other on Saturday.

Modern Wonder is the more favoured of the pair in early betting, sharing favouritism with I Am A Star at $5.50.

Conscious shares the third line at $9.