Seventy-eight horses remain in contention to take on champion Winx in her bid for a record-equalling third Cox Plate at Moonee Valley.

Of the 141 nominations taken last month, 79 remained for the $3 million weight-for-age race on October 28 after first acceptances closed on Tuesday.

Among them are 10 northern hemisphere-trained horses including five from Irish trainer Aidan O'Brien's stable.

O'Brien, who won the Cox Plate with Adelaide in 2014, has Deauville, Johannes Vermeer, Taj Mahal, Lancaster Bomber and Cliffs Of Moher entered but has not paid up for 2015 placegetter Highland Reel.

The other internationals include Godolphin's Saeed bin Suroor-trained stablemates Prize Money and Best Solution and Charlie Appleby's Folkswood.

The Willie Mullins-trained Riven Light and Jane Chapple-Hyam-trained Kaspersky are also first acceptors.

Winx is the $1.50 favourite to join Kingston Town as a three-time winner and she takes another step towards the race when she chases her 20th consecutive win in Saturday's George Main Stakes in Sydney.

Blue Diamond Stakes winner Catchy is one of six three-year-old fillies among the first acceptors while 12 three-year-olds colts are still in contention including unbeaten Royal Symphony.

Royal Symphony and Catchy are among 119 first acceptors for the $2 million Caulfield Guineas for three-year-olds, while Catchy heads the 91 first acceptors for the $500,000 Thousand Guineas for fillies.

Both Guineas races are on the same day, October 14, at Caulfield.