The promising red brindle launched sweetly from box seven and crossed the field to capture the early lead.
West On Cheryl streaked away to a four-length lead during the middle stages and looked to have it all sewn up.
She weakened in the home straight, however, and the strong-finishing Defy The Odds wore down her lead to make things interesting.
West On Cheryl had to dig deep but she had just enough left in the tank, falling across the line to score narrowly.
The Chris Halse-trained chaser has now won six of her 14 starts and has a further five minor placings to her credit.
Nambeelup-based Halse could also have a big say in this Saturday’s Group 1 Sky Racing Perth Cup (520m) final at Cannington, with his youngster Ramifications recording an emphatic nine-length heat victory in a super-quick 29.88sec.