More Joyous made a triumphant spring return at Rosehill on Saturday as her jockey Nash Rawiller declared the champion mare at the peak of her powers.
The eight-time Group One winner was expected to make light work of the Listed Sheraco Stakes (1200m) as a $1.16 favourite but had to fight hard to shrug off one of the outsiders Miss Marx who kicked strongly in front.
But once Rawiller asked More Joyous to go, the crowd favourite quickly put the race beyond doubt as she strode clear to defeat Miss Marx ($31) by 1-1/2 lengths.
Dual Group One winner Streama ($14) also delighted her connections, finishing a short neck away third.
"It's hard to say but I think she's the best she's ever been, potentially anyway," Rawiller said.
"She's really at the top of her game."
Owner John Singleton watched from the mounting yard as his Cox Plate-bound mare notched the 20th win of her career and her fifth in a row after going unbeaten through the Sydney autumn carnival.
"It's just lovely. Everyone said she looked better than she ever has for her first-up run," Singleton said.
"She is just outstanding."
More Joyous will remain in Sydney for the Golden Pendant (1400m) in two weeks before heading to Melbourne to continue on the Cox Plate path.
Black Caviar is out of action this spring and trainer Gai Waterhouse says More Joyous has top billing.
"She's the best female in the country, most definitely," Waterhouse said.
"She won like I thought she would win. She's such a class mare and it's so exciting to be involved with her."
Miss Marx ran the race of her career to split More Joyous and Streama after taking up the running.
"We feel like we won," trainer David Vandyke said.
"We've been beaten by a champion who had to go full bore to beat her."
Streama had to be reshod behind the barriers before the race and trainer Guy Walter was "extremely happy" with the first-up performance.
"She goes to the Premiere Stakes in three weeks and will be better for this," he said.