The wet track bona fides of Fiveandahalfstar are open to interpretation but trainer Anthony Cummings says a rain-soaked Rosehill might not make any difference to the three-year-old's chances of winning the BMW on Saturday.

Fiveandahalfstar is favourite for the $2.25 million weight-for-age race but he is drifting in betting because a hardline stance on his return in three runs on a rain-affected surface show he is yet to run a place when the going becomes worse than dead.

But Cummings said judging Fiveandahalfstar's ability - or lack of it - in the wet on such a small sample of data might be unfair.

Fiveandahalfstar's only run on a heavy track resulted in a close fourth to Dear Demi at Listed level as a two-year-old and Cummings said the effort had hidden merit.

"He drew the inside that day in the Fernhill and the inside of the track was the worst part of it," Cummings said.

"He's had some experience in the wet and he's generally sure-footed and hopefully that will be the case on Saturday.

"If he handles it he's going to be hard to beat and even if he doesn't he might still win."

Asked if he expected the Victoria Derby winner to peak for the BMW, Cummings, sounding just like his famous father Bart, replied: "He'd better.

"He's possibly going to tighten up with the run going into the (Australian) Derby because that's the way he's been trained."

Fiveandahalfstar is out to $3.40 as he tries to become the first three-year-old winner since Grand Zulu beat a Caulfield Cup winner (Mummify) and a Melbourne Cup winner (Makybe Diva) into the placings in 2004.

BMW runners with a proven record in soft ground are Niwot, Sangster, Le Roi, Hathras and Silent Achiever.

Niwot, last year's Sydney Cup winner, has met with $35 to $26 support, Le Roi is into $17 after opening at $26 and Hathras and Silent Achiever have firmed to $7 and $9 respectively.

A victory by the Kris Lees-trained Hathras would seal a spectacular rise for the import who was beaten at Newcastle in early February.

"I'm under no illusions," Lees said. "It's a huge step up from where he comes from to where he's going.

"But he's in form and we are pleased with how he has prepared for the race."