Few wins have meant as much to Michael Costa than Viaductress' breakthrough at city level.

Now Costa is hoping to further repay the faith shown in him by successful owner-breeder David Bentata when Viaductress chases back-to-back midweek wins at Canterbury on Wednesday.

Viaductress stamped herself as a filly of promise while confirming Costa is a trainer on the move when she posted the second win of her career at Warwick Farm two weeks ago.

It capped a significant moment in Costa's career after he trained a Brisbane midweek winner on the same day when Va Va Veni won at Doomben.

"Getting the double was great and winning for David was very satisfying," Costa said.

"David was one of the first owners to support the stable when I started out."

Bentata runs a boutique thoroughbred business with the Coolmore Classic winner Ofcourseican a highlight horse for the Hunter Valley-based operation.

Viaductress is one of the early favourites for the Schweppes Handicap and Costa has opted to engage a claiming apprentice for weight relief to keep the three-year-old filly against her own kind.

"It's a little bit hard to place these three-year-old fillies," he said.

"So we've just got to pick and chose our races and let her go through the grades."

The 3kg-claiming apprentice Koby Jennings takes over from leading jockey James McDonald as Viaductress tries to improve on her record of two wins and two placings from six starts.

Viaductress is challenging McDonald's ride for favouritism.

McDonald will take the mount on the Bryce Heys-trained Positive Charge, a Newcastle winner in November who struck a rain-affected track when resuming at Wyong.

Positive Charge is one of two early favourites for McDonald with Godolphin galloper Unbiased also strongly fancied to win to win the Cafe Culture + Insitu Handicap.

With 83-1/2 Sydney winners in 2015-2016, McDonald has an unassailable lead in the metropolitan jockeys' premiership.