Premier Sydney trainer Chris Waller admits to being as surprised as anyone to learn Single Gaze would be joining his stable.

Connections of the 2016 Group One Vinery Stud Stakes winner decided to sell the mare earlier this year with the expectation this year's autumn carnival was her swan song before she was retired to the broodmare barn in Japan.

But on Tuesday night it was revealed Single Gaze had been sent to Waller by new owner, Katsumi Yoshida's Northern Farm, and was in work at Rosehill.

Waller said he felt for Canberra trainer Nick Olive, who was among the ownership group that sold Single Gaze.

"My first thoughts were 'Gee, I wonder how that'll go down'," Waller said.

"Nick's done a fantastic job with her and as I see it, if I didn't take her someone else would.

"I've said no to a lot of good horses. I train for Mr Yoshida and if I say no to the owner, well I'm pretty much saying I can't train any of his horses."

Waller said Single Gaze would be assessed over the next month and her regular jockey Kathy O'Hara would provide valuable input.

"If she says the horse is going great I'm sure Mr Yoshida will take that into consideration and ask us to find races for her," he said.

"If not she'll just go up and be a mum."

An emotional Olive told RSN927 he was sad and shocked to hear the mare could race on without him.

"It's a bit of a shock to all of us," he said.

"Chris actually called me and let me know.

"We made the decision to retire her. The offer came in, it was a good offer and she was sold on the proviso that she was going to stud in Japan.

"We wanted the best for that horse. We love that horse so much. She affected so many people, not just close to her but in the racing industry, and we just felt that she had gone to the well so many times for us and we made the decision to retire her and move on to the next part of her life and enjoy things.

"If we had any intention of racing on, we would have raced on ourselves."

The northern hemisphere breeding season does not begin until the new year, so Single Gaze could have a spring preparation for Yoshida before going to stud.

This season Single Gaze has registered Group One seconds in the Caulfield Cup, C F Orr Stakes and Ranvet Stakes.