Mr Brightside is now a fully mature racehorse accordong to his jockey Craig Williams.
While Black Caviar was winning races from her two-year-old year through to retirement as a six-year-old, her trainer Peter Moody said she did not reach full maturity until her later racing years.
Mr Brightside is no Black Caviar, but he is about to embark on an autumn campaign in the Group 1 C F Orr Stakes (1400m) at Caulfield on Saturday as a fully mature six-year-old.
The Ben, Will and J D Hayes-trained gelding has graduated from a Group 1 handicap winner to being a multiple Group 1 weight-for-age performer to running second, by the barest margin, in Australia's greatest race, the Cox Plate.
Jockey Craig Williams has been aboard Mr Brightside in 25 of the gelding's 29 starts and has seen him develop and mature along the journey.
That association began with a maiden win at Geelong through to a number of his major victories, although Williams did miss out on Mr Brightside's win in the All-Star Mile and a second win in The Doncaster when sidelined through injury.
Mr Brightside will on Saturday line up for his first start since running second to Pride Of Jenni in the Group 1 Champions Mile at Flemington last November.
Williams rode Mr Brightside in a jump-out at Flemington last Friday and was happy with the gelding's performance and believes the six-year-old can rise to another level.
"We joked about that at Flemington before his run in the Champions Mile and said, because he's always improved, it's going to be scary for his opposition if he does come back and keep improving," Williams said.
"When you see him he just looks more mature in regards to being hardened.
"He hasn't got an bigger, or any taller, he looks fantastic. He hasn't got surplus weight, he's not fat, he just looks more rounded, more seasoned, his muscle definition is a lot firmer.
"He looks the horse that he is on his form guide."
Williams said the biggest transformation from Mr Brightside's four and five-year-old years is that when he turns up for a Group 1 contest, he is ready for a fight.
That fight has arguably set Mr Brightside as Australia's best miler at present.
"It took an international horse to beat him a small margin in the Cox Plate, so he's arguably the best miler to 10 furlong (2000m) horse we have in Australia right now," Williams said.
"He will improve I feel with the run but he's going well enough that he can definitely win on Saturday, and I'm looking forward to riding him."