In-form jockey Rachel King has ticked another box on her bucket list with a polished front-running ride aboard Quackerjack to land a thrilling win in the Villiers Stakes at Randwick.

In a head-bobbing finish, the Mark Newnham-trained Quackerjack ($3.80 fav) fought back right on the line to get the verdict by a nose over Invincible Gem ($12) with Sambro ($19) closing late another short neck away.

The win was King's first at Group Two level and with a Group One in the bag courtesy of Maid Of Heaven in last year's Spring Champion Stakes, the 29-year-old was happy to finally land a stakes-race clean sweep.

"I've been trying to win a Group Two for ages. I've got a few Group Threes and obviously a Group One, but now I've done the Group Two as well and they're all for Mark," King said.

While King felt Quackerjack had held on to win, Newnham was not as confident.

"I thought he got beat," Newnham said.

"I'm sure the other one (Invincible Gem) had a head on him a stride before the line and probably a stride after, but it's the one on the line that matters."

Quackerjack's Villiers held extra meaning for his trainer.

The four-year-old was the first horse to join Newnham's stable when he took out a training licence just over three years ago and has endeared himself as a favourite thanks to his consistency and toughness.

His Villiers win gets him a ticket into the Doncaster Mile in the autumn with Newnham confirming the horse will be aimed at the Group One race.

"He was the first horse I bought at the sales," Newnham said.

"He never gives in. He is such a special horse to everyone in the stable because of his style of racing and how hard he tries.

"He gets a free kick into it (Doncaster) now and he goes in wet, dry. He'll probably only get 51 kilos so it's probably worth having a throw at the stumps."

Newnham praised King's ride while also giving credit to Josh Parr who had been Quackerjack's regular jockey.

Newnham expected Quackerjack to get a lesser handicap than 56kg so he locked in the lightweight King.

"I didn't think he'd get enough weight for Josh to get back on and that was always the plan, so I feel a bit sorry for Josh," Newnham said.

"But he's helped Rachel on giving advice on how to ride him."

Hugh Bowman was proud of the effort of Invincible Gem, who lumped top weight of 59kg and went down fighting.

"She thinks she won, I thought she won, but we didn't get the bob," Bowman said.

Bobbing started second favourite but was never a threat and finished sixth.