Favourite punters did their money at the start of an incident packed Group II Dato Tan Chin Nam Stakes (1600m) at Moonee Valley.
The $4.40 favourite Star Exhibit reared as the barriers opened, dislodging Mark Zahra before continuing on through and then around the field.
Dwayne Dunn was forced to set a strong pace early aboard He's Our Rokkii passing halfway with the riderless horse on his outside, Damian Lane settling towards the rear aboard Bonneval.
Star Exhibit had circled the field and was first into the home straight as Bonneval ($7 - $5) made progress to challenge for the lead, reaching the front 200m out then holding the late challenge of Abbey Marie ($12) to score by a neck with Rhythm To Spare ($16) four lengths further back in third.
Co-trainer Murray Baker, who prepares the mare in partnership with Andrew Forsman, said he was pleasantly surprised with the win.
"She was a fair way behind in condition due to the wet winter we've had at home," Baker said. "She's done nothing but improve since we got here and we know she can gallop.
"It's a pity the way the race was run - Bonneval had a clear passage but I'm not so sure about Lizzie L'Amour, the riderless horse tried to go up her inside and that seemed to unsettle her."
Bonneval is entered in the Caulfield and Melbourne Cups as well as the Cox Plate and Baker said the four-year-old would get her chance
"The Caulfield Cup comes first so that will be the first one, all being well," Baker said. "She won two Oaks last season so I'm thinking she can get further but you never know until you try them.
"For her to run like that at her first start here and after the preparation she's had tells me she should be in for a good spring.
"I thought Lizzie L'Amour would beat her home - she easily beat her home in a trial and we thought if Bonneval could be running on for fifth or sixth we'd be happy."
Damian Lane said he can only see Bonneval getting better.
"She'll improve off that run," Lane said. "She's still got her New Zealand winter coat on her and she'll benefit a lot from the race fitness-wise - it was a good win."
Bonneval is now $9 second favourite for the 2017 Caulfield Cup with CrownBet.