With a flurry of winners in recent weeks, leading apprentice Beau Mertens is mounting a serious challenge for the jockeys' premiership in Melbourne.

But the in-form rider is not getting ahead of himself.

Another two winners at Caulfield on Saturday moved Mertens to 50 metropolitan victories in Victoria for the season, closing the gap even more on leader Craig Williams after he seemingly had a stranglehold on another title only a few weeks ago.

"I'm four behind, so I'm getting close but I won't count my pennies too early," Mertens said after wins on Boom Time and Miss Gunpoweder at Caulfield.

"There's still a few months to go and I'm sure Willo will be back here soon enough riding winners. So I'll just keep my head down."

Williams has been riding in Sydney during the majority of the major autumn carnival Saturdays but both he and Mertens will be in action at Sandown on Monday with Williams booked for eight rides while Mertens has seven.

Mertens will be out to close the gap further on Monday with a careless riding suspension ruling him out of Saturday's Caulfield meeting.

Nicholas Ryan was the last apprentice to win the Victorian metropolitan jockeys' premiership in 2004/05.

Williams will also miss Saturday's Melbourne meeting to ride Big Duke in the rescheduled Sydney Cup.

"I'm not going to go the early crow, but whatever happens, happens," Mertens said.

"If I keep going the way I'm going, I'll be close."

Mertens' rides at Sandown include Stormsabrewing who is at $7.50 in an early market and the Gai Waterhouse and Adrian Bott-trained Necklace who is at $9.50.

Williams' rides includes $5.50 hope Lopartega.

Darren Weir leads the trainers' premiership with 107 wins while the David and Ben Hayes and Tom Dabernig team moved to 87 with three wins at Caulfield on Saturday.

The Lindsay Park team's chances at Sandown include Blue Tycoon who is early favourite in the final race while two-year-old Kharir will try to break through in her third career start in the Yulong Park Handicap (1200m).

Kharir is coming off a last-start second in a Cranbourne maiden.

"She just missed at Cranbourne and should be better for the run," Dabernig said.

"It was her first time in blinkers last start and I'm sure Sandown will suit her better than Cranbourne with the long run in."