Rosdhu Queen maintained her perfect record by making just about every yard of the running in the Jaguar Park Cheveley Park Stakes at Newmarket.
Sent off at 4-1 after having won her previous three races, including the Lowther Stakes at York last time out, Johnny Murtagh's mount just missed the break a little, but soon recovered to head the field.
Heading into the Dip it looked as if she would be swallowed up by Lowther runner-up Baileys Jubilee, but Rosdhu Queen stuck her neck out gamely and quickened up again to win going away by a length.
Winning Express stayed on strongly to take second place, while Baileys Jubilee finished third.
Murtagh said: "She travelled well on her own and didn't seem to mind it.
"She was on the rail and she wasn't getting any hassle.
"She's pretty fast, but maybe she'll mature over the winter.
"It's a quick mile here and maybe she should take her chance in the Guineas."
Rosdhu Queen's trainer William Haggas had expressed doubts about her ability to stay the stiff six furlongs at Newmarket but she allayed those fears in no uncertain terms.
Murtagh, who won the race 12 months ago aboard Lightening Pearl, was keen to make good use of his draw in stall one.
The field split into two groups but two furlongs out they joined together, which was bad news for the 2-1 favourite Maureen as Richard Hughes' partner was left with nowhere to go.
Haggas said: "I can't say enough good things about her - she's really tough.
"Her coat has gone, but she can run.
"I think we ought to enjoy the moment before thinking about next year and consider things over the next four months.
"I didn't think she'd stay six (furlongs) in the Lowther but she went again when she needed to.
"Whether or not she's a Guineas filly I don't know, but why not? She's a good, tough filly."
