Trainer Aaron Purcell has been thrown into the Australian racing spotlight as an unlikely star of this year's Melbourne spring carnival, with Merchant Navy giving him his second Group One win.

The elite colt ($19) stormed home in Saturday's $1 million Coolmore Stud Stakes on the straight 1200m course at Flemington to grab Invincible Star ($6.50) on the line.

It was his first start for Purcell, who was training his own team at Warrnambool when he took over Ciaron Maher's large stable and staff at Caulfield after Maher was suspended for six months in late September.

Emerging star filly Aloisia gave Purcell his first Group One win in last month's Thousand Guineas.

Connections of Merchant Navy elected to freshen him for the Coolmore after his unplaced Golden Rose (1400m) run in Sydney in September and he wore blinkers on Saturday.

"I came to Caulfield with a job to do and obviously winning Group Ones was part of that," Purcell said.

"It wasn't guaranteed it was going to happen but it's a good result for me, good result for the owners and good result for the staff.

"I feel that I'm doing my job well.

"If things hadn't have gone the way they have, I would have been at home at Warrnambool cheering Ciaron's horses home and would've been happy for him."

He said taking over a number of quality horses brought with it expectation and pressure.

"Fortunately I've got very good staff behind me and good facilities and good processes at home.

"Things have been working well and him getting the bob on the line is definitely a very satisfying result."

Merchant Navy races in Darren Thomas' Seymour Bloodstock colours but the colt's ownership group also includes Coolmore which sponsors the race.

Purcell expected Merchant Navy to be strong late but said it wasn't until about the final stride he was going to reel Invincible Star in.

Merchant Navy won by a head, with another short half-head to Formality ($20) in third.

Thomas earlier celebrated the win of John Sargent-trained Luvaluva in the Group Two Wakeful Stakes and said it was special watching Merchant Navy claim the Group One.

Thomas also acknowledged Maher's role in Merchant Navy's career before starting his suspension.

"There's a bloke somewhere in the world with curly hair and I hope he's proud as punch," Thomas said.