Outsider Fat Al led the field from his wide alley as the favoured runners jostled for positions.
Sacred Falls ($10) came out of the pack with Royal Descent ($8.50) launching her challenge and momentarily heading him.
But under hard riding from Purton, Sacred Falls dug deep to get the better of the mare by a half length with Weary 2-1/2 lengths third and Hawkspur ($10) fourth.
"He is a very good colt," Waller said of the winner.
"He won it last year and beat Pierro. I guess there could have been a bit of doubt about his class with the lighter weight then but he's come back close to the topweight this year.
"It really shows how good he is and it's quite unbelievable to get the first four."
Behind the Waller first four, Ninth Legion ($51) ran a bold race for fifth while Japanese visitor Hana's Goal ($51) made up a lot of ground in the straight to finish sixth with her jockey Kyousuke Maruta saying through an interpreter the ground was heavier than she had ever experienced.
Waller said the four horses and maybe My Kingdom Of Fife, would back up in next Saturday's $4 million Queen Elizabeth Stakes.