After breaking a track record at Mornington on debut, three-year-old Runson makes the leap to metropolitan racing on Boxing Day.

And the horse's breeder and co-owner is excited to see the gelding take to the city stage.

Janet Gaist and her partner Peter Harris have a stud farm, Manner Lodge Thoroughbreds, in country Victoria where they bred Runson.

By unfashionable stallion Delzao, Runson almost didn't make it to the racetrack after a life-threatening accident as a young horse.

"He had an accident in the paddock and he punctured his side, almost right next door to his lung and we had to have him bandaged for over a month," Gaist said.

"He was stitched up out in the paddock by a vet, so they saved his life."

Runson, trained by Leon and Troy Corstens, made his debut in a 1000m maiden at Mornington earlier this month, winning by 1-1/2 lengths.

Gaist said it was an unbelievable thrill to see the horse they bred and own win on debut.

"To pick himself up at the 200 metres when I sort of thought he could run second or third, then to go over the line with his ears pricked was just mindblowing," Gaist said.

"We're rapt. We're that excited."

Gaist is looking forward to being trackside on Saturday when Runson runs in the Frank O'Brien Handicap (1200m), but admits it is a "massive ask".

Runson is a well-supported $6 chance with Cool Snitzel the $5.50 favourite.

Troy Corstens also acknowledged it was a jump in grade for Runson.

"But I think he's ready for it," Corstens said.

"I really like him. I've got a lot of time for him.

"The owners bred him and raised him and did basically everything with him and have been extremely patient.

"He's really just coming into his own. He's still a bit of a big baby but I'm happy for him to take his place on Saturday."