Having won the Cox Plate for the first time, Japanese trainer Yoshito Yahagi is keen to return for another Melbourne spring carnival.

The Yahagi-trained Lys Gracieux, a dual Group One-winning mare in Japan, showed her class in Saturday's Group One weight-for-age Cox Plate (2040m) at The Valley to win by 1-1/2-lengths.

Her win came a week after fellow Japanese horse, the Hisashi Shimizu-trained Mer De Glace, won the Caulfield Cup .

The Cox Plate was a race Yahagi had wanted to win since he watched one of Kingston Town's three victories in the race in the early 1980s.

Yahagi was in Australia last year with Chestnut Coat who was unplaced in the Caulfield and Melbourne Cups .

"I will come back here," Yahagi said

"Probably with a different horse."

This year's Cox Plate had been on the radar for Lys Gracieux and her connections since the mare's win in the Group One Takarazuka Kinen in Japan in June.

That victory made her eligible for a $2 million bonus if she also won the Cox Plate.

The Australian government played a part in getting Lys Gracieux to the race by relaxing the quarantine protocols after she raced in Hong Kong and fell short of the 180 days residence in a third country.

"As soon as it was cleared we were happy to come," Yahagi said in the lead-up to the Cox Plate.

Racing Victoria's Paul Bloodworth was instrumental in working with global horse transporters, IRT, to satisfy quarantine officials she should be able to enter Australia.

"It was a big team effort. And then you saw what a superstar she is," Bloodworth said.

Lys Gracieux was one of three northern hemisphere-trained horses to win on Saturday's Cox Plate program, the others being Irish horse Hunting Horn (Moonee Valley Gold Cup) and English-trained Chief Ironside (Crystal Mile).

Bloodworth hopes Lys Gracieux's Cox Plate success will help attract other top Japanese horses but said it would still be a challenge given the weight-for-age Grade One Tenno Sho Autumn (2000m) is on at the same time.

"She would have otherwise run in that if she had not come here," Bloodworth said.

"It's still going to be a challenge but I think this will show Japanese trainers and owners that Australia is a realistic option and the prize money is so good as well."