Even though he had planned Lucia Valentina's assault on Sydney's richest race to the finest detail, even Kris Lees seemed surprised when it actually came off.

After the mare's fourth in the Coolmore Classic, the Newcastle trainer went against his normal pattern and kept her away from the races with just a barrier trial to keep her up to the mark.

The four-week break did the trick and Lucia Valentina ($8) took care of some big names in Saturday's $4 million Queen Elizabeth Stakes (2000m) at Randwick, coming from last on the home turn to score a decisive 2-1/4 length win over the favourite, The United States ($4.60).

Doncaster Mile runner-up Happy Clapper ($8) finished another half length third.

"It's very rewarding when you set a horse for a race so far out," Lees said.

"I just thought I had to do something a bit different, thinking I would be taking on Winx.

"She's so effective at 2000 metres and loves to have her runs spaced.

"I don't know why it took me so long to do it.

"This is my biggest day on a racetrack."

Her win was also part of the biggest day for the mare's New Zealand owner Lib Petagna who also collected the trophy for the Australian Oaks with Sofia Rosa.

Stephen Marsh trains Sophia Rosa and was the former trainer of Lucia Valentina who was sent to Lees to further her career in Australia.

Petagna's bloodstock agent Bruce Perry paid $60,000 for Lucia Valentina and $5000 more the Sofia Rosa.

"We've had a Group Two and Group One on the same day before but never two Group Ones," Perry said.

"It's a big thrill."

The win was even sweeter for Lees as he watched as mare ran into dead ends at the 400m.

"She looked in a lot of trouble on the turn. She dipped and went down on her nose.

"They've been talking about sending her to stud so I might attack them right now and see if I can go another year."

Lucia Valentina's rider Damien Oliver said things got a little dicey but once she got room, it was over.

"Coming to the turn I had a lot of horse and not much room to go anywhere," he said.

"I went up in between a couple as we straightened and I got shut out of that.

"She picked herself up again and just went whoosh."

Oliver had earlier won the Group One Queen of the Turf Stakes on Azkadellia and the $400,000 Provincial Championship final on the Lees-trained Danish Twist.

"You never get sick of it," he said.

"I've been doing this a long time and I'm certainly in the home straight of my career.

"You certainly cherish these moments at the end of your career.

"It has been a wonderful day and I don't want it to end."

The end has come for multiple Group One winners Criterion and Mongolian Khan with their racing careers over after the Queen Elizabeth.

Criterion heads to Newgate Farm in the spring while trainer Murray Baker said the owners would look into stud deals for Mongolian Khan.