Apprentice Ben Thompson is excited to partner a filly part-owned by his parents in a feature race at Caulfield on a day his father could have a cross-code Group Two double.

In Saturday's Group Two Blue Diamond Prelude for fillies Ben Thompson rides the Robbie Griffiths-trained Zarpoya who is part-owned by Jason and Seona Thompson.

Jason Thompson is a prominent greyhound trainer and has three chances, including the favourite, in Saturday night's Group Two Cranbourne Cup for greyhounds.

"Dad's got three dogs running in the Cranbourne Cup on Saturday night for the greyhounds and his attention will be at Caulfield earlier in the day," Ben Thompson said.

"It's good and hopefully the horse gives them a really good ride."

Zarpoya was third in the Merson Cooper Stakes on debut in November and finished runner-up at Moonee Valley last month with Thompson aboard both times.

The filly is at $26 on Saturday.

Ben Thompson said Zarpoya had given her connections a good ride so far and hopes it's just the beginning with a potential Blue Diamond Stakes start a possibility two weeks after Saturday.

"It's obviously exciting riding a horse for my parents and hopefully she can do the right thing by us this Saturday," Thompson said.

"And better yet in a fortnight.

"Obviously it was exciting to run third in a Listed race on Sandown Cup day in the Merson Cooper and she was pleasing first-up at Moonee Valley. Hopefully she can go one better on Saturday."