A low key midweek meeting for most, a milestone first city success for an excited Zephen Johnston-Porter.

It's one to put in the scrapbook and if you talk to good judges it will be the first of many to come for the teenager.

What made the groundbreaking victory all the more sweeter was sharing the spotlight with his older brother Clint Johnston-Porter.

Combined, the brothers won four of the seven races on the programme.

Clint booted home a treble: lifting Bondi's Future in a thriller, Simply Thinkin' and Westcoast Express in another close go.

Zephen scored on the Jim Taylor-trained Cross Statement, giving the gelding every chance outside of the leader, Torpedoman before dashing to the front.

There were a few anxious moments in the straight when Imposing Brook was coming home fast, but Cross Statement had done enough and held on grimly.

After 30 wins in the provincials and six in the country, Zephen was a first time winner in the city.

"I'm very happy about it," Zephen Johnston-Porter told The Races WA.

"The next aim is to have a winner in town on a Saturday.

"It's given me the confidence to keep on improving.

"I'm absolutely love being involved in racing.

"I'm glad to be able to share the day with Clint and do it together.

"Clint's a great rider and punched home three."

Zephen said he can't overstate the importance of having Clint by his side, acting as mentor and adviser.

Clint was a star apprentice in his own right who has now forged a reputation as one of the top bracket of riders in the state.

Clint's ridden over 700 winners since his debut in 2014 including 30 black-type races.

Zephen said he hopes he can successfully follow in the footsteps of his brother.

"One hundred per cent, he's definitely my mentor and idol," Zephen Johnston-Porter said.

"He gives me tips whenever I ask and sometimes when I don't ask.

"The fact he's around really helps, he's been through it all before."

Zephen's win on Cross Statement helped the six-year-old break a string of placings since his previous win two years ago.

It earned high acclaim from Taylor.

"He rides very well, but importantly listens to instructions," Taylor said.

"He did everything I asked him to do on Cross Statement and listens very well.

"I think he's really going to make it."

Zephen has a few days to soak in the win before jetting off to represent WA In the National Apprentice Race Series (NARS) in Hobart on Sunday.

He's looking forward to the opportunity of not only earning points for his state, but broadening his experience and knowledge against interstate riders.

"Definitely, I'm very excited for it," Zephen Johnston-Porter said.

"New riders, new tracks, it will be a great experience."