With long-time jockey Hugh Bowman in the saddle, she forged clear on the final bend at the notoriously tight Moonee Valley Racecourse to hold off a fearless fight from second placed British galloper Benbatl.
"Going to the other side of the world is one thing, coming back and doing well as well as she is expected to is very hard".
Trainer Chris Waller was similarly emotional.
Avilius has thrilled trainer James Cummings with his performance behind Winx in the Cox Plate. In doing so the seven year old wonder from Down Under secured a 29th consecutive victory, 22 of them at group one level, and took her career earnings to more than £12m.
"I don't think I need to say anything, Winx has said everything we need to know", Chapman replied.
Winx had looked relaxed at the barriers before the race, and she was settled quickly in fourth or fifth behind early leaders D'argento and Benbatl.More news: OnePlus Unveils Newest Flagship the OnePlus 6T in NY
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That might be the case, but this time around she beat a high-quality European challenger who was at the top of his game, who was racing over his ideal distance and had been given every chance by his rider, Oisin Murphy.
There had been speculation Team Winx might retire the great mare after her famous fourth Cox Plate but both men said no decision on her future would be made until later this year.
"We're just making sure she's still as good as the year before, or even six months".
Winx is washed down by stablehands at Moonee Valley after a workout.
She is a champion, still gracing the turf at an age when many comparable racemares have had one or two foals and are long consigned to the breeding barn. "Obviously, the day will come eventually when we have to consider retirement and when she is going to have babies".
"We will check her tendons, her joints, bones, bone density, you name it".