Mature-age apprentice Chris Williams has celebrated his first Saturday metropolitan winner aboard Zonk at Randwick for his boss Les Bridge.

Sporting the red and green colours of the veteran trainer's beloved South Sydney Rabbitohs, Zonk was having her first start on Saturday since a bleeding attack in December.

"I'm always apprehensive when they come back from bleeding," Bridge said.

"But she's done it well and he's (Williams) a good kid and big value with the three kilo claim.

"I hope other trainers take notice."

Williams took advantage of a quick getaway with Zonk ($6) leading throughout and holding off the favourite Kapajack ($2.60) by 1-3/4 lengths.

"She improved lengths off her trial," Williams said.

"It's great to get my first Saturday winner and it was for the boss who has done a tremendous job with her.

"At the 600 (metres) I gave her a little click-up and from the 200 she was never getting beaten."

Miss Exfactor ($4.40) had either led or been outside the leader in her starts for Brisbane trainer Tony Gollan but missed the jump at her first run for Joe Pride and finished last.