Peter Snowden has reversed a previous gear change with That's A Good Idea but admits the horse's last-start flop remains a mystery.

That's A Good Idea was one of the favourites when he resumed in the Starlight Stakes last month before beating just one rival home.

It was an uncharacteristic performance from the sprinter who had managed a top-three finish in six of his previous seven starts.

"The only thing I can say is I put visors on him the other day and whether that wasn't enough for him to make him focus," Snowden said.

"Maybe it backfired. I don't know, he just didn't seem himself at all that day.

"But since that he's been fine, he worked very well yesterday morning and good last Thursday morning so I can't fault him."

Snowden has taken the visor off and put blinkers back on It's A Good Idea, the topweight for the Listed Razor Sharp Handicap at Randwick on Saturday.

He is one of two runners for the stable along with Dublin Lass who won the Starlight Stakes last start after returning from a Group Three placing at Flemington during the Melbourne Cup carnival.

The race has attracted a full field of 16 including the Godolphin pair of Mohave and Barbed, who was scratched from Randwick last Saturday in preference for the Villiers Stakes day sprint.

Veteran Monton resumes in the Razor Sharp, four years after he won the Villiers on the corresponding program.