Caulfield Cup favourite Weekend Hussler will have to carry at least 56.5kg if he is to win the race following second declarations on Tuesday.
Weights for the $2,555,000 race on October 18 will be raised by one kilo after the connections of Efficient decided against paying the $770 fee to remain in the race.
His absence has left Pompeii Ruler, with 56kg, as the highest-weighted horse remaining in the race.
Rules stipulate that the minimum top weight for a Group One handicap in Australia must be 57kg.
Mick Price has already stated Pompeii Ruler will start in the Caulfield Cup but should he go amiss, that would leave Weekend Hussler as the top-weight with 57kg.
Eighty horses remain in the running for the race after another 56 fell by the wayside on Tuesday.
Other high-profile horses missing from the list of second declarations were Sirmione, Light Fantastic and Maybe Better.
Tuesday Joy and Zipping were still in the hunt despite their high-profile owners expressing doubts as to whether the pair would run at Caulfield.
John Singleton, owner of Tuesday Joy, desperately wants to win the Melbourne Cup and does not want to risk a weight penalty by winning the Caulfield Cup, for which she is an $18 chance (TAB Sportsbet).
Lloyd Williams has declared favourite Weekend Hussler all but a certainty to win the 2400m staying test, and said he would target other races with Zipping.
Luca Cumani's pair Mad Rush and Bauer and the Godophin-trained All The Good, who are all in quarantine, were also among the second declarations.
Bauer is unlikely to run in the Caulfield Cup as he is too far down in the order of entry list, while All The Good was approximately equal 22nd.
The Melbourne Racing Club will release an official list on Wednesday morning.