Apprentice Beau Mertens gets an opportunity to edge closer to the lead in the Melbourne jockeys' premiership with a full book of rides at Flemington.

Craig Williams holds a five-win advantage in the title race but the reigning premier will be riding at the Group One meeting in Adelaide on Saturday.

"With him in Adelaide it's going to be a little advantage for me to hopefully try to gain a bit on him and keep creeping closer," Mertens said.

Mertens has 52 metropolitan winners in Victoria this season and the 19-year-old admits his haul has exceeded expectations.

"One hundred per cent it has," he said.

"Six months ago I never thought I'd be where I am sitting on the premiership table today, that's for sure.

"It's definitely been a massive season and hopefully I can continue the luck heading into Saturday."

Among his Flemington rides are two early favourites, Pure Pride (race four) and Divine Quality (race five), while six of the nine horses he is booked to ride are at single figure odds.

"It's a big book of rides and a quality book at the same time," he said.

Nicholas Ryan is the most recent apprentice to win a Melbourne premiership in 2004-05, and Mertens admitted it was in the back of his mind.

"But at the moment I'm just looking to focus on doing what I've been doing for the last few months and hopefully things can just keep playing out the way they have been," he said.

The season runs until the end of July.

Mertens still claims 1.5kg in town and leads Ben Allen by 13 in the Melbourne apprentices' premiership.

"That was my goal at the start of the season, to have a crack at winning the apprentice title," he said.

"It definitely looks like it's within reach but I won't count my pennies too soon."