Waller pivoted late to take in the Makybe Diva Stakes after Treasurethe Moment, owned in the same interests as Via Sistina, was ruled out of the race on Monday following a colic attack.
Instead of trialling on Tuesday, Via Sistina galloped left-handed at Rosehill and will be floated to Waller's Flemington base on Wednesday night.
"Nothing really changed, only we didn't trial her on Tuesday and we were only trialling her because it was going to be four weeks between runs," Waller said.
"Now it's only three weeks, so we galloped her left-handed at Rosehill on Tuesday.
"She's come back in good shape and we're looking forward to Saturday's race at Flemington."
Stablemate Aeliana, who finished second to Via Sistina in the Group 1 Winx Stakes (1400m) first-up at Randwick last month, is set to be one of five rivals for Via Sistina on Saturday.
Aeliana, who took out the Group 3 Carbine Club Stakes (1600m) during last year's Melbourne Cup Carnival, arrived at Flemington earlier in the week.
Along with stablemate Lazzura, who runs in the Group 2 Kirin Ichiban Let's Elope Stakes (1400m) on Saturday, Aeliana galloped on the course proper on Wednesday morning to reacquaint herself with the Flemington circuit.