It wasn't with the member of their stable most expected, but Shane and Cassie Oxlade celebrated their maiden Group 1 success after Queman led home a longshot trifecta in Saturday's Oakleigh Plate at Caulfield.

The Strathalbyn five-year-old, who started $17, nosed out $11 chance Hypothetical in a race that strayed from the script with $41 chance Mornington Glory third.

The Oxlades also had well-backed equal second favourite Sghrippa in the race and while he had no luck after a slow getaway, they were not fussed which of their pair won the $750,000 event.

"You get out of bed every day to train a good horse and to win a Group race or a Group 1 is just the pinnacle of anything in our sport, isn't it?" Shane said.

"I don't know if it'll change much in terms of more horses or less horses.

"To be honest, it doesn't worry me. I'm happy doing what I'm doing. We have 12, 14, sometimes 16 in work.

"It's a really small team at home and it's just good for everyone. It's a big kick."

Queman's Oakleigh Plate win was also the first Group 1 win for his sire Mint Lane and second, but first on Victorian soil, for popular jockey Harry Coffey.

Coffey utilised barrier two to position Queman behind leader Hypothetical, who didn't have the company up front that most anticipated pre-race.

Sghirripa was not the only leading fancy to be tardy away, with Asfoora also settling further back than normal and other speedsters Brudenell and Najem Suhail happy to sit off Hypothetical.

Queman and Hypothetical had the race between them from the 250m and at the line it was the South Australian who prevailed.

Mornington Glory was 1-1/2 lengths back with Benedetta slicing through late to grab fourth, marginally in advance of Brudenell and Recommendation with Sghirripa seventh, beaten just 2-1/4 lengths.

That was one place in advance of spruik three-year-old King's Gambit, the $4.20 favourite, who was never a winning chance.

Coffey had to work hard to get down to Queman's 52kg, but he was keen to make the effort after guiding the five-year-old to victory in the Listed Adams Stakes (1000m) and he was thrilled the Oxlades stuck with him.

"Shane and Cassie, they were loyal to me and I'm greatly appreciative of that," Coffey said.

"It's a huge thrill … I've won a Group 1 (before), so I've had that feeling before, but I wanted to do it again so it wasn't a fluke so hopefully they flow on a bit now."