Don't Doubt Marley is one of only three unbeaten horses in the Quezette Stakes but her trainer Robbie Griffiths is under no illusions as to the task ahead.

Don't Doubt Marley faces her biggest test at Caulfield on Saturday in the Group Three race after a maiden win at Geelong and a midweek metropolitan win at Sale in June.

She is one of the outsiders in the Quezette Stakes which includes the unbeaten Petits Filous who has easily won her two starts at Moonee Valley and is an odds-on favourite.

Last start Flemington winner Jalan Jalan is on the second line of betting at $5.50 with unbeaten Adelaide filly Miss Gunpowder at $6.50.

Griffiths hopes he is proven wrong but believes the 1100m against strong opposition will be too short for Don't Doubt Marley.

The race is an important test for the filly and her performance will help the trainer plan whether he presses on to spring races with her or backs off and waits for summer.

"If she runs respectable, and looks like she's going to compete in the spring then we'll keep her in work and aim towards running in the better races over longer journeys," Griffiths said.

"It's a bit of a D-Day run, really.

"I can't imagine her beating the quality of the field over 1100 but I think it's important for us to see where we rank."

Don't Doubt Marley was drawing away on the line to win by three-quarters of a length over 1000m on the Geelong Synthetic track on debut.

The daughter of Not A Single Doubt then fought gamely to win by a half neck over Ayda in a 1200m two-year-old fillies' race at Sale, with three lengths to third in the small field.