Up-and-coming sprinter Rich Jack faces his stiffest test when he takes on weight-for-age company for the first time at Caulfield.

Having not finished further back than fourth in 13 starts that include five victories, Rich Jack is jumping from a Caulfield benchmark 78 success to the Bletchingly Stakes (1200m) on Saturday.

Trainer Carol Heffernan would prefer to wait a little longer but owner David Mackintosh is keen to try him in Group Three company.

"He's a very good owner and that's what he wants," Heffernan said.

"The horse deserves the chance but I worry a little bit.

"He's a good horse but I would have preferred to get his rating up into the nineties or something first."

Rich Jack is one of 11 entries which include dual Group One placegetter Lord Of The Sky, last-start Sir John Monash runner-up Angels Beach and Sandown Guineas winner Petrology.

Heffernan, who lives in Yarra Glen and makes a 2-1/2 hour round trip to Cranbourne for trackwork, says Rich Jack has benefited from "off days" where he can spend time in the dressage arena on her property.

Rich Jack was a keen going horse in his younger days but was now settling a lot better and Heffernan said the dressage sessions helped with his balance.

"It helped him with his settling out in front," she said.

"We're going to be up against a different class of horse on Saturday and I do worry if something takes him on whether he will settle or not."

Darren Gauci, who scored aboard Rich Jack at Caulfield on July 4, will again have the ride.

Heffernan said while Rich Jack was an easy horse to train, he could be a hard horse to ride.

"Darren knows him and he is a horse that somebody has to know," Heffernan said.

"You have to sit cold on him and Darren understands that."

Rich Jack will be Heffernan's first black-type runner since Gold Boss ran in the Debutant Stakes at Caulfield in 1997.