Despite being a last-start winner, Chancey was sent to the boxes as a $23 hope, but defied the odds when she got the jump on her rivals and bounced straight to the lead.
As they approached the finish line, Chancey had challengers coming from everywhere, with five greyhounds within half a length of one another at the post.
Chancey prevailed by a neck over Jet James and Angry Mud Crab, with Buggles and Rulebook not far behind.
In other racing, 405m ace Buddy Be Cool continued his strong form, winning his second race in row in the Ascot Sign Co Mixed Stake.
Buddy Be Cool used his superior early pace to capture the front-running position.
From there, he was never threatened as he cruised away to score by a length and a half over Special Annie in 22.72sec.