Tim Clark is confident Avoid Lightning has done enough groundwork to overcome a distance query when she resumes at Rosehill on Saturday.

The Les Bridge-trained mare has never won beyond 1200m and will have to beat prolific winner and odds-on favourite Catkins to change that statistic in the Millie Fox Stakes.

However, a Group One placing over 1400m and two recent barrier trials have given Clark reason to believe Avoid Lightning won't be found wanting over 1300m on Saturday.

"It probably is a slight query but I think 1300 (metres) at Rosehill will be a bit softer than 1300 at Randwick," Clark said.

"She's drawn a soft barrier too, all those little things help.

"She did place over 1400 metres at the end of her prep in Brisbane, that's probably as far as she wants but for 1300 she's done a sufficient amount of work."

Catkins is a $1.80 favourite to post her 14th career win in the Millie Fox while Avoid Lightning is regarded as her biggest threat at $3.50.

The Les Bridge-trained mare is one five rides for Clark at Rosehill where he will feature in three stakes races.

Clark has also picked up the mount on VRC Oaks runner-up Thunder Lady in the Hobartville Stakes and rides Scream Machine in the Parramatta Cup.