Trainer Robbie Laing believes he has some spring firepower in the rising three-year-old ranks including So Si Bon who will be chasing his first career win at Flemington.

So Si Bon finished second to Southerly Wind on debut at Flemington in a straight-track sprint but things didn't go his way from a wide barrier at Caulfield last Saturday.

The two-year-old colt by So You Think was back in the field and taken wider around the home turn when the leader Armedanddangerous hung out.

So Si Bon ran home for sixth in the 1200m race won by the promising filly Sebrikka and Laing expects the colt to improve over 1400m in Saturday's Murray Cox Handicap.

"He drew second from the outside last Saturday and we had planned to get in about fifth or sixth but they raced in banks of three so he just couldn't get in," Laing said.

"Then when they got to the home turn the leader ran off the track and took three parts of the field off the track, and he was the widest.

"He only got beaten three lengths and just kept coming.

"I think he's a really good colt."

Laing has a number of rising three-year-olds he believes can step up in the spring including So Si Bon, Jaws Of Steel and Ridgway.

The Laing-trained dual stakes winning filly Missrock is back in work and will be aimed at the Group One Thousand Guineas.

Missrock won the Group Three Percy Sykes Stakes at Randwick at her only autumn start in April having returned from a fractured pelvis suffered at her third start in November.

"She spelled at her birthplace, Cressfield Stud, for two months after the Percy Sykes and she arrived home a fortnight ago," Laing said.

"She's going along beautifully."

Laing said Missrock was scheduled to resume in either the Quezette Stakes or Danehill Stakes.