Promising colt Diameter has emerged as a serious contender for this year’s Group 1 $3 million Caulfield Guineas (1600m) after producing a determined victory in Sunday’s 2026 Stutt Stakes results at Caulfield for trainer Chris Waller and jockey James McDonald.

The son of Brazen Beau showed plenty of toughness to prevail in a thrilling finish to this year’s Group 2 $300,000 Stutt Stakes (1600m), edging out stablemate Somethings Burnin’ by a short head, with Scarole another head away in third.

Sent out a well-backed $3.20 chance third-up after unplaced runs in the Up & Coming and Exford Plate, Diameter stopped the clock in 1:37.13 and continued the impressive form he displayed in the autumn, when he won the Listed Fernhill Mile and placed in the Group 1 Champagne Stakes.

Stutt Stakes | Diameter

Jmac at his very best! Diameter takes a narrow gap & takes the lead in the shadows of the post ?

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The victory is likely to earn Diameter a crack at the 2026 Caulfield Guineas over the mile back at the track on October 10, with Waller indicating the prestigious mile feature shapes as the obvious next target.

Waller Quinella Highlights Strong Three-Year-Old Stocks

Waller was delighted to saddle the quinella and believes both colts have bright futures ahead.

“Two nice horses. He’s going great,” Waller said.

“He showed us in the autumn that he’s up to the better horses.

“He means a bit to us being a son of Brazen Beau so it is good to have him for Godolphin.”

Runner-up Somethings Burnin’ also earned praise from the champion trainer despite just missing out.

“He’s a work-in-progress. He still gets a bit keen,” Waller said.

“We wanted to try him over a mile to see where he’s at but he’s likely a prep away so a lot to look forward to.”

Asked whether Diameter would now head towards the Caulfield Guineas, Waller suggested the pathway was straightforward.

“I guess so. It will be good to talk to James (McDonald),” Waller, who chases a third straight Caulfield Guineas victory following on from Private Life (2024) and Autumn Boy (2025), said.

“Having had the experience around here is a big plus as well.”

The trainer also compared his 2026 Stutt Stakes winner to other members of his three-year-old team, including Tron Bolt, who finished fifth behind Warwoven in Saturday’s Golden Rose at Rosehill.

“They’re more the horses suited to shorter distances,” Waller said.

“Tron Bolt will start to come into his own over a mile so how you pair them, I’m not too sure.

“That was a good solid test, the Golden Rose, yesterday.”

McDonald Sees Group 1 Potential

Winning rider McDonald was impressed by the colt’s fighting qualities after overcoming a tricky run in transit.

“Looked a bit dicey at the top of the straight, to be fair,” he said.

“Had a willing partner to get us through that. But he was lucky. He was superior and he did a really good job.”

The champion jockey believes Diameter has the profile of a colt capable of measuring up at the highest level in a fortnight.

“There’s a good race in a couple of weeks here for him and it has Group 1 next to its name, so I could definitely see him figuring in that,” McDonald added.

“He’s on the way up.”

McDonald also praised the colt’s temperament, a quality that should stand him in good stead stepping into elite company.

“He’s a dude. He’s an absolute gentleman,” he said.

“He bounced well and travelled comfortably. If anything, a little bit quiet but he was there for me when I needed it.”

The Stutt Stakes victory prompted an immediate move in the futures market for the 2026 Caulfield Guineas, with Ladbrokes slashing Diameter’s odds from $26 into $9 following the win.

The market move gives four-time Caulfield Guineas winning trainer Waller another strong hand heading towards Victoria’s premier three-year-old mile, with Tron Bolt also expected to improve as he rises in distance after his Golden Rose campaign.

With his first-up win on the board, proven Caulfield form, and a strong endorsement from both trainer and jockey, Diameter has quickly established himself as one of the key contenders for the upcoming Caulfield Guineas, and looks set to play a major role in the spring’s feature three-year-old races.

2026 Stutt Stakes Results