Chris Waller has declared Winx Stakes victor Via Sistina as his No. 1 seed for the Cox Plate.

Chris Waller will look to split up his stable big guns after producing the trifecta in the Group One Winx Stakes with former European mare Via Sistina showing her class to topple Zougotcha and Fangirl.

The premier trainer saddled up six of the 12 runners in Saturday's 1400m feature and dominated the finish as Via Sistina ($11) snuck up along the inside to run down Zougotcha ($6.50) by a half-head, Fangirl ($2.40 fav) flashing down the outside late to finish a long neck away third.

It was the winner's third Australian start and followed an emphatic Ranvet Stakes (2000m) win in the autumn and a runner-up finish behind Pride Of Jenni in the Queen Elizabeth Stakes (2000m).

"Obviously, she's a very smart horse and I'm privileged to be training horses like her," Waller said.

"It was a beautiful ride from Kerrin [McEvoy]. He didn't go around a horse, saved ground and had plenty of horse topping the famous Randwick rise. She was strong all the way to the line."

Waller will get his Winx Stakes squad home before locking in their next assignments but says the Group 1 Makybe Diva Stakes (1600m) is the main option for Via Sistina.

"The plan was the Makybe Diva in three weeks," Waller said.

"I've just got to split them up a bit now - all three could have won a Group One race if their stablemates weren't there, so I don't want to waste too many.

"Vis Sistina is probably our number one seed for the Cox Plate, unless Fangirl wins like she did in the King Charles (Stakes) again."

McEvoy was having his first race day ride on the winner and said the fact the middle-distance galloper managed to sprint so well fresh was a great sign.

"She really motored the last furlong, so fantastic training effort to see her do that first-up at that level, and the world is her oyster this prep now," McEvoy said.

"She's just a winner basically."

Zougotcha turned in a brave effort after doing some early work to secure a position behind leader Tropical Squall, while Waller was relieved to see Fangirl find the line in her comeback from a life-threatening injury in the autumn

"The barrier draw wasn't kind to her when they came out and it probably cost her a little bit more than Via Sistina, where she had the nice run," he said.

"It would have been fitting to get a win, but I don't think the owners of the first three horses will be disappointed."

Via Sistina gave Waller a Group race double after he earlier took out the Show County Quality (1200m) with Joliestar.