Sweet Idea has often been the bridesmaid at the highest level.

But the consistent mare got the Group One win she deserved, storming home to win the $400,000 Galaxy at Rosehill on Saturday.

The Gai Waterhouse-trained mare's win first-up in Saturday's 1100m sprint came two years after she was third in the Golden Slipper at the corresponding meeting.

Sweet Idea finished second in three other Group Ones last year but she has also four Group Two races during a career which has netted more than $2 million in prize money.

"She's an outstanding mare and I'm so thrilled for the connections. It's everything they've wanted," Waterhouse said.

"They just wanted the Group One and it has just eluded her that little bit.

"Blake (Shinn) rode her magically. He gave her time to settle. He let her get a breather and she just was too good the way she stormed home."

Shinn elected to let Sweet Idea find her feet and had her travelling midfield with cover as well-backed favourite Deep Field ($4.60) raced across and took up the lead from his outside gate.

Wearing blinkers for the first time, Deep Field opened up a three-length lead on the rest of his rivals headed by Chloe In Paris and Kuro.

But he couldn't go on with it in the straight and weakened out to finish 11th.

Shinn angled into the clear shortly after straightening and stormed down the centre of the track to race past three-year-old Kuro ($10) who fought on for second, 2-1/4 lengths from Sweet Idea ($18).

Miracles Of Life ($11) made a sustained run for third, another short half-head away.

Kuro was attempting to give trainer Joe Pride his second Galaxy win in two years after Tiger Tees won last year.

Shinn said Sweet Idea travelled well and showed a great turn of foot.

"The horse is so deserving of a Group One win and what a great style she did it in," Shinn said.

Tommy Berry told stewards Deep Field raced too keenly.

"He pretty much took control after 150 metres," he said.

"He wouldn't come back to me and he was never going to finish off."