Ken Fythe had one instruction for apprentice Tom Sadler when he booked him for his grand old campaigner Rockpecker at Caulfield on Saturday.

"Just ride him like Craig Williams does," Fythe said.

"It's asking a lot, but if he does that he'll have a real good chance."

Rockpecker has won an average of one race for each of his nine years and Williams has ridden him in seven of those victories, including his past four.

"They've got something going together, Craig understands him," Fythe said.

The problem for Rockpecker's connections is that Williams is riding in Japan, so a substitute had to be sought and Sadler got the job of returning the old horse to the winner's list in the Victoria Cup (1440m).

Fythe and Rockpecker have something of a cult following, the Leongatha trainer with the flowing beard and the veteran horse are one of the most popular and enduring combinations in Victorian racing.

As well as his nine wins, Rockpecker has been placed 15 times and has earned almost $700,000, making him Fythe's best horse by a long way.

He is also a tribute to his trainer's judgement and his methods.

Fythe, his sister and his granddaughter fell for Rockpecker when they discovered him at a horse sale in 2004.

"We just liked him straight away," he said.

"So we bought him very cheaply and it has been a pretty lucky ride since then."

Rockpecker didn't race until he was three and the late start combined with a leisurely life between races in a paddock in Gippsland has kept him mentally fresh and physically sound.

One of the few problems he's had in his career occurred during the past winter when the wet weather brought on a foot abscess which has taken a while to overcome.

Fythe puts the horse's mediocre form at his two runs this time in down to the foot problem, but he believes Rockpecker is now ready to do his best.

All he asks is that he be ridden the same way as when his most successful partner is on his back.

"Craig always rides him kindly, that's the way he likes it," Fythe said.