Rather than staying at the rear of the field, Jonker made a bold mid-race move with the Jackie Burrows-trained runner, and it paid off when they took out the $17,000 feature.
Burrows gave Jonker instructions to make her own luck in the race after she and and Yamato Nadeshiko could not find clear air in her last start at Gore.
The jockey followed those instructions perfectly.
"I said [to Jonker] don't be unlucky, make your own luck.
"At Gore we ended up wide and you just can't get around at Gore, so it was good today."
Understandably, Burrows was pleased with Jonker after her daring ride.
"She is my little apprentice and I am proud of her."
Jonker's mid-race move let Yamato Nadeshiko set up an unassailable lead and the horse won by three-and-a-half lengths at the finish.
Thought That fought well to hold second placing after over-racing. Teddytwinkletoes finished well to take third.
The victory was Yamato Nadeshiko's third in 12 South Island starts for Burrows.
The horse was sent South by Otaki trainer Howie Matthews after she developed barrier problems.
Since joining Burrows, Yamato Nadeshiko has got rid of her bad barrier tendencies and performed consistently.
"Howie Matthews sent her down because she wouldn't jump out of the gates up there.
"She is an awesome little horse."
Balcairn trainers John and Karen Parsons had a big day out, winning four races including the Central Otago Summer Cup at Omakau yesterday.
The Parsons stable took the 1400m feature after Tomm Jones sprinted off a good speed for a four-length win for rider Gosen Jogoo.
While some of his rival jockeys went to war before the home turn, Jogoo sat off the speed before launching Tomm Jones for a big finish.
The Parsons stable and Jogoo combined for more wins at the meeting with Letsbringiton, Hoofbeat and Te Quiera.
