Easing All-Star Mile favourite Arcadia Queen is running out of chances to contest the $5 million race.
Lame on Thursday after casting a shoe, Arcadia Queen failed a further veterinary examination on Friday despite being reshod.
But last spring's Mackinnon Stakes winner will be given until race morning on Saturday when Racing Victoria (RV) vets examine the Perth-trained mare for a third and final time.
RV vets told stewards Arcadia Queen's degree of lameness in her front right leg had deteriorated between the first and second inspections.
As a result, she has lost her place as an outright betting pick for the world's richest 1600m race at Moonee Valley.
Drifting to $4.40, Arcadia Queen is now sharing favouritism with New Zealand mare and last-start conqueror Probabeel.
Probabeel has been a standout of the Melbourne autumn carnival with her two wins including success at Group One level over Arcadia Queen in the Futurity Stakes at Caulfield.
But trainer Jamie Richard is hoping a forecast for rain does not impact too much on the track condition, given it is likely to nullify Probabeel's ability to accelerate faster than most horses.
"I'm just hoping the rain doesn't arrive at the Valley tomorrow," he said.
"If (the track) got to slow that would be OK but if it got to heavy we are in real trouble."
The prospect of a wet All-Star Mile, and growing doubts about Arcadia Queen, will help the cause of Russian Camelot.
The brilliant four-year-old has three wins from five starts on slow ground and has been set for a first-up win after a top-10 Melbourne Cup finish at his most recent start.
While all eyes will be on Arcadia Queen on Saturday morning, Sydney mare Shout The Bar will take her place in the race after she was passed fit following a second examination on Friday.
