New Zealand-bred colt Ranting (NZ) (Zoustar) will face his biggest test to date when he steps out in Saturday’s Gr.1 Coolmore Stud Stakes (1200m) at Flemington.

The Troy Corstens-trained son of Zoustar was a last-start winner of the Gr.3 Blue Sapphire Stakes (1200m) and Corstens admitted the three-year-old would have to be on his best behaviour to score in elite company.

“Ranting can still do a little bit wrong,” he said. “You saw in the Blue Sapphire that he pulled extremely hard. He’s not going to be able to do that on Saturday in the grand final against this opposition.”

He said the key to Ranting was to get him to switch off so he could use his explosive finish and he was pleased with how he had come through his gut-busting win in the three-horse Blue Sapphire Stakes.

“I was actually surprised how well he came through that. We’re very pleased with the way that he’s done and I think we’re on track for Saturday,” he said.

Corstens was happy with Ranting’s work on Tuesday at Breakfast with the Stars at Flemington, saying he wasn’t asked to do much, running home his last 400m in 23.6 seconds.