Thoughts about the Adelaide Cup with Purple Smile are likely to strengthen if the stayer can win at Moonee Valley on Saturday.

The David Hayes and Tom Dabernig-trained four-year-old won a midweek benchmark race over 2400m at a Mornington metropolitan meeting last start and is favourite for the Melbourne Signage Concepts Handicap (2500m).

"I think he'll be hard to beat," Dabernig said.

"He's really hit his straps now that we've got him out in distance and he's a horse that's never been out of a placing.

"He's an up-and-coming stayer."

Purple Smile rolled along in front last start and then responded after hitting a flat spot to win by two lengths.

The son of Zabeel took six starts to break his maiden and has now won two of his nine races with seven seconds.

"He backed up when he won last start and it's only 10 days from his last start to this so it's all a little bit quick but he seems to be coping fine," Dabernig said.

The Listed Bagot Handicap (2800m) on January 1 at Flemington could be a consideration if Purple Smile was to step up again but Dabernig pinpointed the Adelaide Cup (3200m) in March as a potential longer-range target in March.

"Who knows where he'll get to but at the moment he's been very consistent and racing well," Dabernig said.

Dabernig rates Purple Smile as the best of the stable's chances at Moonee Valley.

Two-year-old Haybah is the only juvenile with race experience in the Cactus Imaging Plate (1000m) but Dabernig is wary of the first starters, including odds-on favourite Headwater.

Headwater is by Exceed And Excel out of Oakleigh Plate winner River Dove.

Haybah was beaten 3-1/2 lengths in second behind the Mick Price-trained Secret Agenda at Moonee Valley at her second start.

"She (Haybah) should run well but if there's something smart in there they might be too good for her," Dabernig said.