Ron Quinton reckons the reason why Master Harry will parade in perfect health before the Carrington Stakes also explains the sprinter's struggle for form.

"He looks great, as a stallion would," Quinton said. "You couldn't fault him on his looks.

"He's in good order the little bugger but he's a six-year-old (stallion) and he's starting to realise what it is all about now.

"And that is getting in his way a bit."

Master Harry has already spent one season at stud but despite standing as a a Group Two-winning three-year-old, he struggled for patronage.

He joined Quinton's stable earlier this year, winning an 1100m benchmark sprint at Rosehill and held that form in two runs before spelling.

But in the same number of runs this campaign, Master Harry has been a source of frustration for the Randwick trainer.

"I thought his first-up run was OK but he was disappointing last time and I'm just hoping now," Quinton said.

Master Harry is the outsider of a Carrington Stakes field at Randwick on Wednesday that has been reduced to seven runners after the scratching of Pampelonne.

The Chris Waller-trained Heart Testa is the $2.50 favourite to post a breakthrough stakes win.

A four-year-old, Heart Testa has a winning strike rate of better than 50 per cent and he will be out to improve on two Group Three and two Listed placings.

His most recent stakes placing came when he was edged out by Aeronautical in the Razor Sharp Handicap.