Anthony Cummings is never one to shy away from a Group One challenge and in Fiveandahalfstar he believes he has the armour to take down It's A Dundeel in Saturday's Australian Derby.

The only time the two three-year-olds have met was in the Victoria Derby in the spring with Fiveandahalfstar the winner and It's A Dundeel the unplaced favourite.

It's A Dundeel went to Flemington as a Group One winner of the Spring Champion Stakes while Fiveandahalfstar went there off victory in a Benchmark 72 at Rosehill.

After four close seconds this autumn, Fiveandahalfstar was back in the Group One winner's circle at Rosehill on Saturday, winning the weight-for-age BMW over 2400 metres, the same distance as the Derby.

His win was not enough to persuade bookmakers he had the wood on his main rival with the TAB tightening him from $4.40 to $4 for the Derby but also firming It's A Dundeel from $1.70 earlier in the week to $1.50 by Sunday.

Trained by New Zealander Murray Baker, It's A Dundeel has won the Randwick Guineas and Rosehill Guineas this campaign with blinkers helping him to stay in touch with the field before unleashing his customary devastating sprint.

In contrast, Fiveandahalfstar's natural style is to lead and Cummings is aware his charge could be a sitting target.

"It's A Dundeel has a great turn of foot and we have to work out a way to deal with that," Cummings said.

"But Fiveandahalfstar is at the top of his game and ready."

Cummings gave Fiveandahalfstar a familiarisation tour of the new parade ring at Monday's low-key Randwick meeting.

"I just wanted him to see it so it wasn't new to him on Derby day," he said.

The Mick Kent-trained Philippi, winner of Saturday's Tulloch Stakes for three-year-olds is seen as a challenger to the top pair and is at $9 for the Derby.

Trainer Donna Logan said the New Zealand Derby winner Habibi, third to Norzita in the Vinery Stud Stakes and a $13 Derby chance, was "99.9 per cent" certain to be saved for the Oaks on April 27.