The John Oxley colt, trained by Mark Casse and ridden by Luis Contreras, faced three rivals in the mile and one-eighth event over the Polytrack, after the scratch of Malibu Moon.
The Kentucky-bred stumbled at the start but settled into third position as Holiday Promise led the field through an opening quarter-mile in :24.54 and a half in :48.38.
Contreras urged Prospective into the lead at the top of the lane, bumping with fellow Casse trainee Patrioticandproud in upper stretch, before driving clear a length and three quarter winner in 1:51.08 over the Polytrack.
"My horse stumbled a little bit coming out of the gate, but after that he relaxed pretty good," said Contreras.
Casse, who entered the weekend as Woodbine's leading trainer with 21 wins from 104 starts, admitted he was concerned with Prospective's awkward start.
“When they came out of the gate, and he (Prospective) stumbled so hard, I said, ‘Oh no, not again,'" said Casse. “But he got it done."
The conditioner figures the multiple stakes winning colt has a number of options for his next start.
"He’s had a pretty good campaign," said Casse. "We’ll talk to Mr. Oxley. I’m not sure that synthetic is his favourite. He likes dirt. So we may travel out of the country for his next one (start).”
Prospective paid $2.90 to win, combining with Patrioticandproud for a $9.10 exactor. There was no place or show wagering available.