Tatra has been ruled out of Saturday's Gloaming Stakes, putting his bid for the Group One Spring Champion Stakes in doubt.
The colt had an elevated temperature on Sunday, forcing trainer Peter Snowden to reconsider his options for the Ming Dynasty Quality winner.
"It's thrown that spanner in the works as to what we do with him now," Tatra's trainer Peter Snowden said.
"He seems fine again now, this morning (Tuesday) he was good and his blood is almost back to normal.
"We've got the dilemma whether to go to the Dulcify Quality next week and then back up (in the Spring Champion) or just abort Sydney and look to Melbourne."
Snowden says the Spring Champion (2000m) on October 6, which he has won twice in the past four years, is now "highly unlikely" for Tatra who is on the third line of betting with TAB fixed odds at $9.
"Missing this run on Saturday, it was crucial for me to get him to the next one," Snowden said.
"Not running this Saturday I think is a blow to his chances of getting towards the Spring Champion Stakes.
"I wouldn't like to run in the Dulcify and back up the next week. I don't think that's the right sort of plan for him."
Tatra's stablemate Proverb is at $13 for the Spring Champion Stakes on the back of his second in the Ming Dynasty.
Proverb runs in the Spring Stakes at Newcastle on Wednesday where he will be out to confirm a start in the Group One.
The Gai Waterhouse-trained Proisir, the reigning Spring Champion Stakes favourite at $4.20, also runs in the Newcastle race while It's A Dundeel, second elect for the Spring Champion at $8 is in the Gloaming.