Via Sistina has quashed doubts over her heavy track credentials with back-to-back wins in the Winx Stakes.

Chris Waller described it as a "Foxplay moment" but just as the mighty Winx did eight years ago, Via Sistina found a way to lift against the challenge of a stablemate to post her ninth Group One win at Randwick.

Having her first start since taking out the Queen Elizabeth Stakes in April, Via Sistina had a battle on her hands in Saturday's Winx Stakes (1400m) when barn mate and Australian Derby winner Aeliana challenged strongly in the straight.

The younger mare momentarily looked as though she might claim racing's reigning queen but Via Sistina's championship qualities shone through and she prevailed by a neck.

Waller was moved to recall the corresponding race eight years ago when Foxplay almost upstaged Winx in what was then known as the Warwick Stakes.

"It was almost a Foxplay moment, wasn't it?" Waller said.

"We've got a couple of decent mares on our hands."

Via Sistina captured the race last year before she was beaten on a heavy track in the Makybe Diva Stakes (1600m) then went on a three-race winning streak highlight by her Cox Plate triumph.

Waller was vocal in his concerns about running his stable star first-up on a heavy 10 surface on Saturday and said they wouldn't be completely alleviated until he was certain she had come through the effort without issue.

Speaking on Sydney radio on race morning he said he would have been happy to see Saturday's card postponed a day or two to provide the elite horses with the best possible racing surface and he didn't back down from that stance.

However, his key point was that racing administrators look at resting Sydney's two main tracks, Randwick and Rosehill, during July when the grass doesn't grow and recover.

"I didn't have doubt we could run today. My doubt was, where are we after today? In two weeks' time, four weeks' time?" Waller said.

"(Australian Turf Club track manager) Michal Wood does a fantastic job and (ATC senior racing official) Nevesh Ramdhani. They've got a fantastic team. We went and walked the track before and it's safe. They've got a great track.

"But I want to help them in July and relieve them so they've got fresh ground to work with.

"These horses are worth so much money and the punters put so much into it week-in, week-out we've got to have the best surface.

"They need Via Sistina, not just winning today. They need Via Sistina winning second up, third up, fourth up, and the horses behind her they've got to come through the race.

"We've got to have all the best horses for as many times during the spring as we can."

Via Sistina is likely to follow a similar path to the Cox Plate as last year while plans for Aeliana remain fluid, although Waller has no doubt she will "get her time to shine".

Sydney Cup winner Arapaho was also responsible for an outstanding return, finishing third, while Ceolwulf rattled home from last for fourth and will have his next start in the Chelmsford Stakes (1600m).

Via Sistina gave Waller and jockey James McDonald the middle leg of a Group race treble after they claimed the Toy Show Quality (1100m) with Autumn Glow and Show County Quality (1200m) with Lazzura.