Retirement looms for Sydney racemare Secret Admirer after she runs in the $500,000 Doomben Cup on Saturday, trainer Grahame Begg has revealed.

Asked if the Group One race could be Secret Admirer's last, Begg said: "It could very well be."

Secret Admirer is one of the outsiders in pre-post betting but Begg is sure the mare will run much better than her $16 quote suggests she will.

"I might be missing something but you would think the form out of the Queen Elizabeth Stakes would be good enough for her to figure on Saturday," Begg said.

Secret Admirer was beaten five lengths into fifth place to the globally-ranked Reliable Man in the Queen Elizabeth Stakes at Randwick last month and Begg saw merit in her run.

"She was good through the line coming along the inside of the track," he said.

Secret Admirer galloped in the wet at Doomben on Tuesday morning but she is expected to get her preferred firmer going on Saturday.

"The course was very wet this morning but she was the first one out and the forecast is for improving weather," Begg said.

The Doomben Cup holds special significance for Begg because Eye Of The Sky's 1990 victory marked the Randwick trainer's first Group One win.

A rising six-year-old, Secret Admirer has banked almost $1.4 million in stakes.

Her finest moments have been on her home track with Group One wins in the Flight Stakes and Epsom Handicap.

Secret Admirer has been winless since her 2011 Epsom victory but she has been placed another seven times at Group One level.

Michael Rodd rides Secret Admirer for the first time on Saturday.

Ranvet Stakes winner Foreteller ($3) is shadowing the Peter Moody-trained Lights Of Heaven ($3.50) for Doomben Cup favouritism with Lamasery the only other runner under double figures at $5.50.