Apprentice Beau Mertens is having a breakout season.

Winning doubles at the two city meetings in Melbourne so far this week has Mertens, son of retired Group One-winning rider Peter Mertens, second in the metropolitan jockeys' premiership.

The 19-year-old, who rode his first city winner 11 months ago, is in a battle with fellow young gun Ben Allen for this season's apprentices' premiership in Melbourne.

Mertens has 37 metropolitan wins this season, one ahead of Damien Oliver and two ahead of Dwayne Dunn and Allen but 15 behind Craig Williams.

He has six rides at Moonee Valley on Friday night and four at Flemington on Saturday, three for trainer Henry Dwyer and the other for the Lindsay Park team.

He rides Snitzelwood for Lindsay Park trainers David and Ben Hayes and Tom Dabernig in the New York Racing Association Grand Handicap (2000m).

A win on Zunbaqa at Sandown on Wednesday gave Mertens his first winner for Lindsay Park.

"They have been supporting me for the past two or three weeks and I've been dying to get a winner for them," Mertens said.

"I went to trackwork at Flemington the other week and did a couple of gallops for them. And they're definitely rewarding me."

Mertens rides Tan Tat Beauty, Boomwaa and Stormsabrewing for Dwyer on Saturday.

Indentured to Mick Kent, Mertens says support from some top stables has been a key with 12 of his 57 wins statewide this season for premier trainer Darren Weir.

"My boss lets me do a lot of freelance so that does help, and I get the rides from it," Mertens said.

Mertens is keen to increase his lead in his bid for the junior title

"You don't really have many shots at winning a metro apprentices' premiership," he said.

"Once you get to town you sort of get one solid season of really getting a few wins on the board.

"It would definitely be a massive achievement to win it. At the moment I'll just focus on my riding and once we get a bit closer I'll start thinking about it a bit more."