A visiting trainer trying to build some momentum with a new stable and an apprentice hoping to make an impact in one of the world's toughest riding jurisdictions combined for a timely win at Warwick Farm on Wednesday.

Caulfield trainer Henry Dwyer's decision to run Mendivil in Sydney instead of Mornington turned out to be the right one in the Australian Turf Club Handicap (2200m).

It also provided Victorian apprentice Damien Thornton with a winning springboard into Sydney racing.

Thornton is staying with Gerald Ryan with an eye to a three-month stint with the Rosehill trainer and he couldn't have wished for a better start as Mendivil lifted under his vigor to beat Tenby Lady.

"The horse in all his races since I've had him has shown a tendency to need that sort of riding," Dwyer said.

"He has no turn of foot whatsoever.

"He's just a confidence and build momentum-type horse. The sooner you get going on him the better."

Dwyer has tried to stock his yard with tried horses and Mendivil has been an instant success - and a terrific advertisement for a trainer who has honed his skills in the stables of Robert Smerdon and Lloyd Williams.

"I've got nine in work at Caulfield and this horse is the only one up and running at the moment," the 29-year-old said.

"This is my first interstate runner so to get a winner is a great thrill and hopefully it will open a few doors."

The midweek meeting also provided another apprentice with a breakthrough victory.

John Kissick rode his first winner for Chris Waller since joining the premier trainer on a three-month loan when Rivariva ($21) beat the favourite Vitello ($2.60) in a deceptive finish to the Husson @ Vinery Handicap (1400m).

Most on course thought Vitello had done enough on the outside to get the photo but Rivariva put his head down when it counted.

Rivariva was the third of four successive winners for Waller with Earnest Desire, Define and Murder Of Crows completing his quadrella.

The sequence also included a trifecta for the trainer in the Become An ATC Sponsor Handicap (1400m) with Define beating Canossa and All Cerise.