More Joyous will have set a weight-carrying record for a mare if she is to defend her Doncaster Mile victory.
The eight-time Group One winner has been given topweight of 59.5kg for this year's Doncaster on April 20, two kilograms more than she carried in 2012.
Cuddle (1936) and Sunline (2002) carried 59kg and 58kg respectively to win what is regarded as Australian premier mile race.
Multiple weight-for-age winner Manighar, who returns from injury in Saturday's Chipping Norton Stakes, is the second highest weighted horse in the Doncaster on 58kg in handicaps announced on Monday.
Last autumn Manighar won the Australian Cup, Ranvet Stakes and BMW but his winning run was halted by More Joyous who beat him in the Queen Elizabeth Stakes.
Shoot Out, runner-up in the Doncaster last year, goes up half a kilo to 57kg while star colts All Too Hard and Pierro have 56kg.
Dual Group One winner Secret Admirer has 53.5kg and is the highest weighted mare after More Joyous.
Her two Group One wins have come over the Randwick Mile in the 2010 Flight Stakes and the 2011 Epsom Handicap.
Pierro, a stablemate to the Gai Waterhouse-trained More Joyous, maintained his unbeaten record in Sydney with victory in Saturday's Hobartville Stakes.
He is the $5 Doncaster favourite in TAB's early markets ahead of All Too Hard ($8), More Joyous ($11), Proisir and Rebel Dane ($13) and Shoot Out ($17).