Star apprentice Beau Mertens has notched a couple of milestones and edged closer to another with a winning treble on Flemington Finals Day.

The Melbourne jockeys' premiership leader's first milestone on Saturday was reaching 100 winners in Victoria for the season, which he brought up with his victory on Schism in the Leilani Series Final.

He then added the Listed A R Creswick Series Final on Highland Beat which meant he outrode his apprentice's claim.

The win on Highland Beat was Mertens' 70th metropolitan winner in Victoria this season and his 80th overall.

It is a significant achievement for the 19-year-old given he only rode his first city winner in April last year.

"It's obviously a big thrill," Mertens said.

"And to do it so quickly and to ride my last one in a Listed race for the Lindsay Park team is a big achievement for me. It gives me a lot of confidence."

Mertens started Saturday one win ahead of the suspended Craig Williams in the Melbourne jockeys' premiership but has extended that lead to four with his winning treble which he completed in the final race of the day, the Silver Bowl Series Final, on Willi Willi.

Willi Willi was due to be ridden by Williams before he incurred a careless riding ban last Saturday which meant he missed two city meetings this week.

"I'm rapt," Mertens said.

"Obviously that was one of Craig's rides. So it's unfortunate for him, but another man's loss is another man's win.

"I was happy to pick up the ride and he was very tough."

There are six city meetings remaining this season.