Champion jockey Nash Rawiller has clinched the Sydney jockeys' premiership with his first ride of the day at Warwick Farm on Wednesday.

Rawiller rode tough stayer Diamond Jim to victory in the TAB Rewards Handicap to put him 3-1/2 wins in front of Hugh Bowman.

Bowman, who finished second in the race on the favourite Msongari, was left with only three other rides at the midweek meeting.

It is the third Sydney jockey's title for Rawiller, who staged a whirlwind finish to chase down Bowman in the last month of the Australian racing season.

"I was pretty pumped getting here today because I thought Hugh had good rides, better than they looked on paper," Rawiller said.

Rawiller said he couldn't remember a better patch of riding form than the one he has experienced in the run towards his latest premiership success.

"It's been the best two months, including a couple of Group Ones in Queensland, that I've had as a jockey," he said.

Rawiller went into Wednesday's meeting with 21 winners since the start of July, a run of form that resulted in him reeling in Bowman's lead at Randwick last Saturday.

He missed three months of the season because of injury and suspension but said his time on the sideline had provided him with the motivation to chase a premiership.

"At the time that was all I could use to drive me to get back and do well," Rawiller said.

Rawiller will celebrate his premiership when he embarks on a working holiday during the Darwin Cup carnival.