The consistent Coup Ay Tee has upstaged his much-hyped stablemate Bayrir to win the Winter Challenge at Rosehill with trainer Chris Waller rapt with both performances.

A Group One winner in America, Bayrir was sent out the $3.10 favourite for his Australian debut on Saturday and looked as if he might reward punters until Jason Collett steered Coup Ay Tee through a gap to snatch the race by half a length.

The 1500 metres of the Listed race was the shortest distance Bayrir had ever run over but one well within the comfort zone of Coup Ay Tee, the winner of seven races from 1200 to 1600 metres.

"There wasn't much room," Collett said.

"I had a lot of horse underneath me on the turn.

"I looked to come out then went to go back in trying to find some room.

"The horse was going that well he wanted to take that small gap."

A former New Zealander, Coup Ay Tee is raced by Kiwi businessman Ray Coupland who has invested heavily in the thoroughbred industry.

Coup Ay Tee's first foray into stakes company came just two weeks ago when he ran third to Under The Sun in the Winter Stakes.

Under The Sun was among his opponents again and in contrast to the praise he earned for that win, jockey Thomas Huet was admonished by stewards who said Saturday's ride was not of a metropolitan standard.

A drifter from $2.80 to $4.80, Under The Sun jumped from barrier two but ended up three-wide with stablemate Kinnersley leading.

Kinnersley finished third while Under The Sun was two lengths away in seventh.

Waller was encouraged by Bayrir's effort and said his next start was likely to be the Premier's Cup (1800m).

"He was travelling like the winner but it was still very pleasing," he said.

"We'll see how he comes through this but the 1800-metre Listed race will suit."

Jockey Hugh Bowman agreed.

"I didn't expect him to show a turn of foot at 1500 metres but he will love it when he gets over further," he said.

"He is a very serious horse."