Improving two-year-old Diomedes has had to survive a protest before continuing his sire Golden Archer's great start to his stud career.

Diomedes became Golden Archer's eighth Australian winner and ninth overall when he won Wednesday's Mount Franklin 2YO Plate (1350m) at Doomben.

Brad Pengelly on second placed Naked fired in a protest alleging Robbie Fradd on Diomedes had checked him at the 75m mark.

"Robbie came out and I had to take hold. If he doesn't do that I run on and beat him by a half length," Pengelly said.

Fradd said he had moved out but had taken hold of his horse and would have won by further than the three-quarter length margin if he had not steadied.

Stewards agreed Fradd had shifted his ground but thought the interference was minor and dismissed the protest.

A former top juvenile when trained by Peter Moody, Golden Archer has been standing at stud at Raheen on the Darling Downs.

Studmaster Basil Nolan said it had been a great first season for the Group winning stallion.

"He has had eight winners in Australia and one in Singapore. I think even better is to come," Nolan said.

Diomedes, who cost $40,000 as a yearling, continued a long run of success for owner Tony Valos and the Bryan and Daniel Guy training combination.

"Tony is our longest standing owner and he has been great for us," Daniel Guy said.