Veteran trainer Clarry Conners is preparing for a sad farewell to the best horse in his stable.

Dear Demi, the 2012 VRC Oaks winner, has run her last race.

Conners had been getting her ready for Saturday's Group One All Aged Stakes and admitted he was shocked when he heard John Singleton had decided to retire her.

"I am disappointed because she went really well in a 1200 metre trial on Friday and I though she would go well in the All Aged," Conners said.

"I understand she has been sold to Japan.

"She has been a wonderful mare. Her Oaks win was obviously a highlight but she ran some other great races.

"She ran second in the Oaks in Sydney and was placed in the Caulfield Cup and the Mackinnon Stakes.

"I picked her out at the sales and she has been a special horse but she will be going up to (Singleton's) Strawberry Hill Stud on Monday."

Dear Demi earned more than $2 million during her 40-start career.

Conners will now rely on Decision Time as his only runner at Randwick on Saturday.

The injury-plagued gelding tuned up for the Hall Mark Stakes with an 810m barrier trial win at Warwick Farm on Friday.

Because of his various problems, the seven-year-old has had just 25 starts but still managed to amass more than $1.5 million prize money, more than a third of that from his second in the 2010 Golden Slipper won by Crystal Lily.

He has won nine races from 900 to 1400 metres.

The Group Three Hall Mark is over 1200 metres with Brenton Avdulla to ride.