Dominant Cox Plate winner Via Sistina has shot to outright Melbourne Cup favouritism despite not yet being a confirmed starter for the race that stops the nation.

Via Sistina looks primed to take on the 3,200m staying test at Flemington on November 5 after smashing Winx's race record in the 2,040m Group 1 feature at Moonee Valley on Saturday.

The Chris Waller-trained seven-year-old mare jumped as third-favourite and won Australasia's weight-for-age championship by a record eight lengths from pre-race favourite Prognosis.

But connections of Via Sistina — bought by Yulong Investments for $5.5 million in December last year — will "let the dust settle" before deciding whether to back her up in the Melbourne Cup.

"We're not going to rule anything out at this stage … we're just going to enjoy the moment," Yulong general manager Vin Cox said after the Cox Plate triumph.

If she starts and is successful, Via Sistina would become only the second galloper to claim the Cox Plate-Melbourne Cup double this century, after legendary mare Makybe Diva (2005).

Three-time Melbourne Cup winner Makybe Diva is one of just five to have completed the feted double, along with Nightmarch (1929), Phar Lap (1930), Rising Fast (1954) and Saintly (1996).

James McDonald steered Via Sistina to her stunning Cox Plate victory and was in awe of the display.

"She won like Winx … it was just a phenomenal performance," McDonald told the Seven Network.

It was McDonald's third consecutive Cox Plate triumph — after wins with Romantic Warrior last year and Anamoe in 2022 — and his 100th Group 1 victory.

Via Sistina had been in serious doubt to start the race after throwing McDonald during trackwork four days earlier.

The incident forced a complete rethink of her preparation by Waller, who wasn't interested in taking credit for the mare's quick recovery.

"We've done these things before," the trainer told Seven.

"Forget what happened Tuesday, she's a good horse and (it was) my job to prove it."

Waller has won the Melbourne Cup once, when McDonald steered Verry Elleegant to victory in 2021.

AAP