Bel Sprinter is primed to run a blinder in his Group One Galaxy defence on Saturday but trainer Jason Warren concedes the weather could pose a problem.

Bel Sprinter has not won since his explosive last-to-first performance in The Galaxy (1100m) at Rosehill a year ago.

But the gelding gave his trainer an indication he was on target for his shot at a second Galaxy success with a fast-finishing fourth in the Group Two Challenge Stakes last start, his best finish since his second in the KrisFlyer International Sprint in Singapore last May.

Rain is forecast for Sydney until Friday, putting doubts in the trainer's mind.

"He ran into a wet track in the Moir Stakes and didn't really like it," Warren said.

Warren is also hoping his stable star's racing pattern at Rosehill doesn't play against him.

"Horses don't seem to be making ground on it which is a concern," he said.

If a rain-affected track presented itself it would enhance the prospects of another Galaxy winner, Temple Of Boom who is among the 16 nominations.

Temple Of Boom, the 2012 winner, performs best in the wet while his half-brother and Tony Gollan-trained stablemate Spirit Of Boom - last Friday night's William Reid Stakes winner - prefers a firm surface.

Joe Pride would be another hoping for rain as noted wet tracker Rain Affair is nominated.

Warren said Bel Sprinter was thriving in Sydney.

"He's in terrific order. He'll run a blinder on Saturday," Warren said.

Bel Sprinter, to be ridden by Craig Newitt, has topweight of 58kg with last year's runner-up and Lightning Stakes winner Snitzerland on 56.5kg along with Challenge Stakes minor placegetter Famous Seamus.

Warren said it was hard to compare how Bel Sprinter was going compared to last year given he was a year older and would be having his third run this preparation while he went to the Galaxy first-up last year.

"He probably needed the first-up run in the Oakleigh Plate, being a year older," Warren said.

"The horse isn't showing the brilliance he was last year but he's carrying more weight.

"It's hard to compare how he's going, but I think he's going pretty well."