Trainer David Payne has earmarked Colesberg as a Group One contender after the two-year-old gelding scored an upset debut win at Warwick Farm.

The victory continued a golden run for part-owners Wilf Mula and Paul Whelan who in the past 18 months have seen Flying Artie stamp himself as a Group One-winning star colt while French Fern, Kentucky Miss and Dublin Lass have won stakes races.

They had another cause for celebration on Saturday when Colesberg ($26) upstaged $1.60 favourite Single Bullet in the two-year-old handicap over 1200m.

After settling last, Colesberg entered the straight the widest runner and stormed home to win by three-quarters of a length from Single Bullet with Callmetrouble ($13) narrowly grabbing third.

Single Bullet's defeat put paid to any chance of him running in the Gold Coast Magic Millions Classic on a one-week back-up.

The Group One Champagne Stakes (1600m) is now Colesberg's main autumn target with Shinn and Payne both confident the horse will be better over further.

"He's a lovely horse," Payne said.

"I think there's improvement in him on this run so we'll see where we go now."

The win prompted Payne to liken Colesberg to Chimboraa who he trained to run second in the Champagne in between Prized Icon and Divine Prophet who won the Victoria Derby and Caulfield Guineas respectively as three-year-olds.

Chimboraa was sold to Hong Kong owners for $1.4 million after the Champagne but Payne is not about to rush his heir apparent's juvenile career.

"If you start chasing money, you ruin them so we'll just see how he pulls up and then look for something later," he said.

"We might give him a short little spell, a couple of weeks out and bring him back."

Single Bullet's jockey Ben Melham refused to blame defeat on the wet track.

"He just wanted to race a bit today," Melham said.

"He's a nice horse, but maybe a prep early."