Waikato mare Costume has pulled off a major upset in the Group One Livamol Classic in Hastings, possibly denting the Australian hopes of one of her opponents.

Costume started the race at odds of $52 after failing to get into the top nine in either of her first two runs this season.

But an increase in trip to 2040m brought the best out of her and she showed the form which won her the Group One International Stakes at Te Rapa in February.

In a tight finish, jockey Michael Coleman got Costume through a narrow gap in the straight and she just beat Shuka by a nose.

Costume's stablemate Soriano, which looked the winner 100m out after a dream rails run, was not much further back in third, with Zonza close in fourth.

"I got a good run up before the corner and she made good ground. It was a little bit tight between runners that last 200m but she stuck her head out when it counted. She's brave," Coleman said.

Costume, a Savabeel mare, is prepared by Graeme and Debbie Rogerson in Hamilton for her owner-breeder Garry Chittick.

The disappointment of the race was hot favourite Puccini, who was perhaps disadvantaged by having to lead the field back up to runaway leader Weissmuller and faded in the straight to finish midfield.

The New Zealand Derby winner was expected to head to Australia for the Caulfield Cup or Cox Plate if he ran well at Hastings but his effort may cause a rethink.