Apprentices get few chances to prove themselves as big race riders.

But Damien Thornton will get an opportunity to boost his career immeasurably in Saturday's Group One ATC Sires' Produce Stakes (1400m) at Randwick.

Chad Schofield won a Cox Plate as an apprentice on maiden Shamus Award last year and Thornton will partner unbeaten colt Time For War for his master Gerald Ryan in Saturday's feature.

Thornton earned his Group One shot when he rode Time For War to successive wins at Rosehill including the Group Two Pago Pago Stakes (1200m).

Time For War has hung out noticeably at both his outings but Thornton says his knowledge of the tricky horse will help him in the Sires' Produce Stakes.

"He's got plenty of quirks about him," Thornton said.

"He didn't drift out in his trial so he surprised me when he did it in the Pago Pago Stakes.

"I think it's (caused by) race day pressure and a little bit of greenness comes into it as well."

The two-year-old has led at both his wins which leaves Thornton with simple tactics.

Thornton said Time For War's racing style meant he should be effective at his first attempt at 1400 metres.

"Hopefully he can lead again," Thornton said.

"He'll be able to travel and relax a lot longer and give a good kick at the top of the straight."

Heavy ground would not trouble Time For War as the youngster won the Pago Pago Stakes in similar conditions.

Time For War will start the $1 million contest from barrier seven in a field of 11.

Bookmakers have installed Time For War as an $8 chance in early Sires' betting with his stablemate Believe Yourself the $3.80 favourite.

The filly finished fourth to Mossfun in the Golden Slipper and will be one of three Sires' runners backing up from Saturday's juvenile feature along with Unencumbered (10th) and Cornrow (15th).