A foot abscess has been blamed for Diamond Tathagata's dismal return to racing but trainer Mark Newnham is still taking no chances ahead of the Run To The Rose.

The Mark Newnham-trained colt was unable to replicate encouraging barrier trial form in the Rosebud Stakes (1100m) at Rosehill last month, though there was a mitigating factor.

Racing for the first time since the Group One Sires' Produce Stakes in April, Diamond Tathagata finished last in the Rosebud, nine lengths behind Menari.

Newnham said Diamond Tathagata had a foot abscess burst two days after the Run To The Rose.

"I was relieved to find some reason behind the disappointing performance," he said.

"He trialled well leading into it, he beat Comin' Through and Winx and finished alongside Pariah in the other.

"The form out of the trials he contested has been good."

Newnham admitted the 1100m in the Rosebud was short of ideal but he still expected a more polished performance as Diamond Tathagata targets the Group One Golden Rose on September 23.

He was pleased with Diamond Tathagata's work on Tuesday and the colt will sport blinkers for the first time on race day.

"He just couldn't get near the speed and on Saturday, 1200 on a fast track they might just help him take up a better spot," he said.

Diamond Tathagata drew barrier four with Corey Brown when the 11-strong field was finalised on Wednesday.

And although Tulip and Goodfellas did not accept for the race, Newnham acknowledged it was still an ominous challenge.

"There's nowhere to hide. It's a full dress rehearsal, it's nearly the Golden Rose over 1200. We'll find out whether he's up to that level or not."

Newnham has opted not to run six-year-old mare Selita in the Group Three Sheraco Stakes (1200m).

"It looks too strong. It's nearly a Group One mare's field, they're the best mares going around," he said.