Rosehill Guineas winner Dealer Principal will be sidelined well into next year because of a leg injury.Trainer Anthony Cummings said Dealer Principal injured himself in a simple trackwork accident last week, bringing an end to a frustrating spring campaign."The horse was cantering on the sand track when he stumbled and he was lame when came back to the stables," Cummings said.Veterinary tests showed Dealer Principal had cracked an accessory carpal bone."It's an injury that isn't uncommon in thor

Rosehill Guineas winner Dealer Principal will be sidelined well into next year because of a leg injury.

Trainer Anthony Cummings said Dealer Principal injured himself in a simple trackwork accident last week, bringing an end to a frustrating spring campaign.

"The horse was cantering on the sand track when he stumbled and he was lame when came back to the stables," Cummings said.

Veterinary tests showed Dealer Principal had cracked an accessory carpal bone.

"It's an injury that isn't uncommon in thoroughbreds," Cummings said.

"The main cause in an over-extension of the knee-joint."

The injury rules Dealer Principal out of Sunday's $200,000 Canberra Cup - and next year's autumn carnival.

"Time is the best thing with an injury like this," Cummings said.

"He'll have six months in the paddock and then he'll return for next year's spring carnival.

"I'll be looking forward to working with a fully mature horse by then."

Dealer Principal's injury completes a difficult preparation for the Group One winner who was tipped as a serious Cox Plate contender after claiming the Rosehill Guineas last season at just his fifth career start.

Dealer Principal was placed only once in five runs and had his campaign switched from Melbourne to Sydney in a bid to find form.

A Hong Kong sale then fell through at the 11th hour, prompting Cummings to set the galloper for the Emirates Stakes.

Dealer Principal didn't disappoint with his fifth placing to All Silent and Cummings was preparing the gelding to return to staying distances in the Canberra Cup and next month's AJC Summer Cup.

Cummings's spring winners Duporth, Red Lord, Road To Rock as well as Group One-placed Turffontein, are spelling until next week.

Duporth, who gave Cummings his first success in a $1 million race by winning the Golden Rose, is expected to resume alongside Turffontein in the Lightning Stakes at Flemington on January 31.

Road To Rock will be given a Sydney Cup campaign while plans for Red Lord include a one-run lead-in to the Doncaster Handicap.