The manager of leading Victorian jockey Glen Boss kept ringing trainer Stephen Theodore for 10 days trying to secure the ride on in-form Road Trippin' at Flemington.

He knew that Stephen Arnold, who steered the gelding to victory over 1600 metres at Caulfield on July 3, could not make the 54kg on Saturday.

"I don't often get the privilege to have jockeys of his stature riding for me," said Theodore.

"It's going to be great to have him."

Road Trippin' is a brother to the ill-fated and highly talented two-year-old Crack A Roadie, who was hit by a truck and killed when he escaped from his handler outside Theodore's Cranbourne stable.

After his Caulfield win on July 3, Theodore was looking ahead to racing the three-year-old in the $200,000 Cranbourne Cup in October but victory in the Hiraji Handicap (1600m) on Saturday will lift the bar.

"A win would set a new benchmark and I would aim a little higher and give him a look at Flemington over a mile in the Emirates Stakes," he said.

He said Road Trippin' had been slow to mature but he hasn't missed a step.

"He was running well in Group races in one of the best years in a decade in the three-year-old season," Theodore said.

"He's won against the older horses and he's given everybody a glimpse of what he can do."

Theodore's other entry at Flemington is Caitlin's Spirit in the Coolalinga Handicap (1100m).

He said the gelding has never been down the straight at Flemington but a fast tempo would suit him.

"He's drawn outside and we're hoping he can pop up when he needs to as long as the track is not too heavy," Theodore said.