New Zealand-bred six-year-old Callsign Mav showed all of his fighting qualities when landing the Gr.1 Sir Rupert Clarke Stakes (1400m) at Caulfield on Saturday, providing popular heavy-weight jockey Jamie Mott with his first elite-level victory.

A three-time Group One winner in his native New Zealand for Hastings trainer John Bary, who remains in the ownership, the son of Atlante dug deep to score narrowly from I Am Superman and Tuvalu.

At his sixth run for Victorian trainer Danny O’Brien, Callsign Mav was ridden off the speed set by Buffalo River and despite being under pressure turning for home, mustered his best under 57.5kgs to record the fourth Group One win of his career in the lucrative A$1 million feature.

O’Brien was savouring his 23^rd Group One victory and said the step back to handicap conditions had worked the oracle.

“He is a three-time Group One winner in New Zealand, so he has done it at the top level over there and he has run in Cox Plates and All-Star Miles here,” O’Brien said.

“So just a little bit softer conditions today and little bit softer race and he is a tough racehorse. He has won plenty of races so it is great to see him a Group One winner in Australia as well.”

O'Brien was quick to sing the praises of Mott, who began as an apprentice with the trainer almost 20 years ago.

"He's just been such a gifted rider who's worked so hard over such a long period of time with his weight," he said.

"If Jamie was four or five kilos lighter, he'd be a top-three metropolitan jockey.

"He rides as well as anyone and he's going to be a very popular victor here today. There are so many people that have got so much admiration for Jamie."

Mott said he had long had faith his Group One time would come and he was delighted it was on an O’Brien-trained runner.

"We've had a great, long association for many years and he was fantastic to me as an apprentice,” Mott said. "It's really pleasing to get a win for him.

"I always knew a Group One win was coming.

"I'm one for working hard and always believing in what you are doing. Give up is not an option. I put myself in a good spot weight-wise and mind-wise this campaign and I'm thankful to Danny and the wonderful connections for keeping me on Callsign Mav.

"They deserve it and the horse does as well."

Callsign Mav will now likely take aim at the Gr.1 Toorak Handicap (1600m) back at Caulfield on October 8.

Bred by Windsor Park Stud, Callsign Mav is from the first crop of Mapperley Stud stallion Atlante, a son of Fastnet Rock who won the Gr.1 New Zealand 2000 Guineas (1600m) for Murray Baker and Andrew Forsman. The stallion died after just two seasons at stud.

Astute horsewoman Emily Holmes purchased Callsign Mav for just $3000 as a weanling at Karaka from the Windsor Park Stud draft on behalf of some of the owners.

The now gelding is out of the three-win Volksraad mare Raadisi, a half-sister to Group One winner The Party Stand.