The three-year-old was slow to muster speed in Thursday's 1200m-feature and settled worse than midfield, usually a recipe for trouble on the small circuit.

But Parr steadied the ship and once Diamond Thunder got to the outside in the straight, the prolific winner would not be denied, arriving in time to nail Hightail by a half-neck.

The runner-up's Peter and Paul Snowden-trained stablemate Leviathan was another neck away.

"He was just a bit hesitant in the first 50 metres of the race but there's nothing like versatility, and that goes for horse and jockey," Parr said.

"Plan C was deployed and Plan C was a beauty."

Diamond Thunder took his record to five wins from seven starts on Thursday and while trainer Mark Newnham admitted he had some concerns early in the race, he was confident once the three-year-old balanced up in the straight.

Diamond Thunder will have one more run in the Vo Rogue Plate (1400m) at Eagle Farm on December 28 before heading to the $2 million Magic Millions Guineas (1400m) at the Gold Coast two weeks later.

"That will give him a run over 1400 leading into the Magic Millions," Newnham said.

"He's just got a really good will to win.

"Once he started to come I was confident enough he would get home over the top of them. It was close but what he showed today is once he steps up over 1400 metres in Queensland he's going to be suited."

Diamond Thunder firmed slightly to be $7 second pick for the Guineas behind Alligator Blood, while Hightail had his price slashed from $51 to $15.

Australian Associated Press