"It's pretty exciting, as it's my second Group 1 on her," Johnson said.
"She's pretty quirky but the team do a good job with her and she has delivered the goods [yesterday].
"I had a chat to Jamie, and watching some of the previous races, they haven't been coming too wide, so we opted to stay in a little and it's paid off.
"I was mindful not to go too soon on her, as it was a mile, so I had to count to 10, which jockeys aren't too good at.
"I did have a few thoughts go through my head when I saw the tangerine [Prise De Fer] outside me and they weren't too pleasant, but we still won."
Stable representative Libby Richards was quick to praise the ride by Johnson and the effort by runner-up Prise De Fer in his first attempt in Group 1 company.
"She [Avantage] was just so brave and seeing her go the inside and Prise De Fer to the outside, I knew they were going to fight it out, which was so exciting," she said.
"Danielle rode her beautifully and they are an awesome group of owners who are here to celebrate the win with.
"Prise De Fer also showed he was up to Group 1 company, which is very cool."
Avantage has now won nine of her 16 starts, three of those at Group 1 level for more than $1.3 million in earnings.
- NZ Racing Desk