On straightening, Williams eased Mr Brightside three wide to loom up to the leaders and under hands-and-heels riding raced clear to a 1-½ length win from Alligator Blood ($3.60) with Osipenko ($15) a long neck away third.
Mr Brightside had his tongue out as he raced up the Flemington straight as Ben Hayes, who trains the gelding in partnership with brothers Will and J D, joked that he was sticking it out to the opposition.
"It was the first time I've seen him with his tongue out, so he's sticking his tongue out at them," Hayes said.
"But he won well and he's such an exciting horse. We're so proud of him, an incredible horse.
"Flemington's the number one track in Australia and to have a horse of his quality to be able to win and win like he did, albeit in a small field, I think he really stamped his authority again today.
"He's definitely the horse to catch now which is very exciting for us and I hope we can enjoy the ride a little more."
Hayes said the Group 1 King Charles III Stakes (1600m) at Randwick on October 14, a track and distance Mr Brightside is unbeaten at, was likely to be the gelding's next outing.
"We'll see he pulls up first, we've always got to see how the horse pulls up," Hayes said.
"But at this stage we are leaning towards Sydney, the King Charles.
"He's undefeated over a mile at weight-for-age and just won here very impressively so I think it's a good race to head to and that's two weeks into a Cox Plate which would be pretty good for him."
