For the first time in her 12-start career, Vain Queen was not the favourite when she went onto the track for the Group Three Mumm Stakes at Flemington.

But it didn't stop the straight track specialist from posting her seventh career win, downing $4.60 top pick Bounding by a comprehensive 3-1/2 lengths in Thursday's 1100m sprint.

It was Vain Queen's fourth win from five starts down the Flemington straight course and the mare thrilled trainer John Sadler both before and during the race.

"She looked the best she has ever looked in the birdcage but I knew she would have to bring her best to win," Sadler said.

"It was more like a Group Two race with some really good mares engaged, but she was dominant.

"It's very exciting and there is a Group One for her I'm sure.

"I'm thinking a race like the Robert Sangster in Adelaide would be a good target.

"Races like the Lightning might be a bit rich. There are a lot of good sprinters around at the moment."

Damien Oliver brought Vain Queen out of the pack inside the final 400 metres and she stretched out to overtake Bounding.

Shamal Wind ($4.80) and Lilliburlero ($15) dead-heated for third, just behind Bounding who has run three seconds in four Australian starts this spring.

"She was smoking in behind them and when she got the run she just exploded," Oliver said.

Bounding's jockey Mark Du Plessis could only shrug.

"She's found one better again," he said.