Jameka has exacted Group One revenge on her last-start conqueror Humidor in emphatic style, spacing the Australian Cup winner by 6-1/2 lengths in the BMW at Rosehill.

The winner of the Caulfield Cup last spring, the Ciaron Maher-trained Jameka was the equal favourite in the Australian Cup two weeks ago when Humidor collared her to win by a long neck.

The step up from 2000m to 2400m on Saturday was in Jameka's favour, as was the pre-race certainty she would have Lasqueti Spirit to follow.

"It was a super effort today and what a ride by Hughie," Maher said.

"It was one of her target races and I'm just rapt to get it done."

Three-year-old filly Lasqueti Spirit led by many lengths but found the going tough in the run home and weakened to finish fifth as the older horses came at her.

Exospheric, third in the Australian Cup, finished in the same position, 1-3/4 lengths behind Humidor.

Bowman was thrilled to win the race for Maher.

"I won the VRC Oaks for Ciaron a few years ago on Set Square and I've had a limited but very good association since," he said.

"This mare was dominant in winning the Caulfield Cup. You had to see it to believe her run in the Australian Cup.

"She made my job easy. I just had to keep her happy, keep her in her rhythm."

"I had to have confidence in her ability and just wanted to stay close enough because if Lasqueti Spirit didn't stop then I could reel her in but not use up too much petrol if the swoopers came."

Jameka started the $3.10 favourite with support coming following the withdrawal of Ranvet Stakes winner Our Ivanhowe, which failed a vet test on Friday.

Last year's Australian Derby winner, Tavago, was also among the favoured runners at $4.40 but his future is uncertain after he pulled up lame.

Co-trainer Trent Busuttin said he appeared to have a suspensory injury.

"He copped a bump 30 or 40 metres after the start but whether it happened then, I don't know," Busuttin said.

"We'll put him on the float back to Melbourne and get him assessed.

"He will obviously need a long time out."

Humidor is also likely to return to Victoria, while Jameka's next start could be against Winx in two weeks in the $4 million Queen Elizabeth Stakes at Randwick.

If that is the case, Maher will have to find a new jockey, with Bowman stuck to the champion like glue.

Maher also has a European campaign in mind for Jameka.

"Depending how she comes through, it's definitely something to think about," he said.

"It's a great conundrum to have."