A Cox Plate win has been elusive for trainer Gai Waterhouse and her wait continues after outsider Pornichet finished fourth to Winx.

Chris Waller has celebrated his biggest win while fellow champion trainer Gai Waterhouse will have to wait at least another year for an elusive Cox Plate victory.

Waterhouse has won a Melbourne Cup with Fiorente in 2013, a Caulfield Cup with Descarado in 2010 and six Golden Slippers among her 134 Group Ones but she is yet to claim a Cox Plate.

"I'll be here again next year," Waterhouse said after Pornichet finished fourth in Saturday's $3 million feature at Moonee Valley.

Pornichet was a $61 outsider in Saturday's race but Waterhouse said the imported horse showed he deserved to be there with his performance to finish fourth, although the champion trainer conceded Winx was dominant.

"I would've been happier if we won, but the mare stuck him to the wall," Waterhouse said.

"He travelled behind the second horse (Criterion), got a little bit of a squeeze at the top of the straight but he ran fabulous."

Waterhouse has twice trained the runner-up in Cox Plate and has finished third on three occasions.