As the regular rider of Famous Seamus and Avoid Lightning, Tim Clark faced a dilemma when both horses were entered for the Group One Galaxy on Saturday.

He opted to ride Avoid Lightning with the conundrum ending happily for the jockey when Famous Seamus' trainer Noel Mayfield-Smith scratched the horse from Rosehill.

Mayfield-Smith said a wide barrier draw had convinced connections to save Famous Seamus for the William Reid Stakes at Moonee Valley next Friday night with Clark booked for the Melbourne mount.

Avoid Lightning will take her place in the Galaxy, a race which provided Clark with his first Group One win on Typhoon Zed in 2008.

He won it again on Atomic Force three years later and said Avoid Lightning had the right profile to deliver him a third.

"I've had a bit of luck in the race and I'd like to keep that going," Clark said.

"A few of the main chances have drawn wide and she's got a nice alley which should suit her.

"Although she is pretty adaptable with distances, I think 1100 to 1200 metres is her pet trip so she gets that here, and she should get a hot speed."

In eight starts for trainer Les Bridge, Avoid Lightning has posted four wins and three placings, including a last-start third behind Catkins and Plucky Belle in the Millie Fox Stakes.

Those mares have subsequently franked that form with Catkins second in the Group One Canterbury Stakes and Plucky Belle winning the Coolmore Classic.

While Avoid Lightning's recent form is against mares, she scored a comprehensive June Stakes victory over the males last winter.

Clark's only concern heading into Saturday is the prospect of a firm track.

Avoid Lightning has performed in all conditions but is superior on rain-affected ground.

"I'm not too worried about taking on the boys. The real test will be trying to beat them on a dry track," Clark said.

"But she is a horse that always gives her best."

Avoid Lightning is a $9.50 chance with Deep Field favourite at $3.80.

The scratching of Famous Seamus means first reserve Atmospherical gains a start and she is at $11.