Newcastle trainer Benjamin Smith got his start in racing as a stablehand for Bart Cummings.

Now Smith will test out what he learnt from his old boss when his sprinter Testarhythm lines up against Shamalia from the Bart and James Cummings stable in the Starlight Stakes at Rosehill on Saturday.

More than a decade ago Smith worked for the Cups legend in Sydney between shifts managing a city pub at night.

"I finished at the pub, went home and had a sleep, then I'd go and do the afternoon at Bart's and then head back off to work," Smith, 31, said on Thursday.

He had this routine for six months before going full-time with Cummings.

Smith went from Cummings' stable to work with well-known horsemen Greg Bennett and Peter Snowden before setting up his own stable in 2011.

The easy-going trainer, who grew up in Scone in a family involved in the industry, says he always loved horses and racing.

"I knew I wanted to train," he said.

"And I knew I had to be around the best trainers to learn as much as I could and give myself the best chance."

Smith was given Testarhythm in the middle of a preparation.

It happened when the seven-year-old's former trainer Darren Smith wasn't allowed to nominate runners as Racing NSW stewards investigated the presence of the banned substance Cobalt in some of his runners.

"It wasn't ideal, but he's (Testarhythm) an old professional and he's pretty smart," Smith said.

"He settled in well."

Testarhythm is in a tough Starlight Stakes field that includes Hawkes Racing-trained favourite Our Boy Malachi and last-start winner Dothraki.

But Smith expects the inside barrier to help Testarhythm.

"He's probably drawn to the get the run of the race," Smith said.

"And he's got a good record at Rosehill so we expect a forward showing on Saturday."

Smith's Newcastle stable has only eight horses but the young trainer, who works with his younger brother Daniel, says this is by design.

"We want to do a good job with a small stable. You can really concentrate on being hands on," he said.

"(And) we're starting to get a bit of better quality (horse) now."