Headline jockey Craig Williams is aiming for a Group One double in Perth on Saturday before he leaves Australia to take up a six week contract in Japan.Williams, who won this year's Caulfield Cup and Cox Plate, missed the winning Melbourne Cup ride on French horse Dunaden through suspension.He bounced back from that disappointment with four winners at Sandown on Saturday, the final feature meeting of the Melbourne spring.He aims to keep the momentum going at Ascot on the Mark Webb-trained Avienu

Headline jockey Craig Williams is aiming for a Group One double in Perth on Saturday before he leaves Australia to take up a six week contract in Japan.

Williams, who won this year's Caulfield Cup and Cox Plate, missed the winning Melbourne Cup ride on French horse Dunaden through suspension.

He bounced back from that disappointment with four winners at Sandown on Saturday, the final feature meeting of the Melbourne spring.

He aims to keep the momentum going at Ascot on the Mark Webb-trained Avienus in the $1 million Railway Stakes (1600m) and Ortensia, prepared by Paul Messara, in the $1 million Winterbottom Stakes (1200m).

Two years ago Williams rode Ortensia, then trained by Tony Noonan, to an impressive victory in the weight-for-age Winterbottom which until this year was a Group Two race.

The jockey won last year's Railway when he guided the John Thompson-trained Gathering to an all-the-way victory.

Avienus contested her second successive Cox Plate (2040m) at Moonee Valley last month finishing 13th of 14 to Williams' mount Pinker Pinker after her second to Descarado in the Caulfield Stakes (2000m).

Last start the six-year-old came from from behind at the 800m to finish fourth to Vintedge in the Group Two Matriarch Stakes (2000m) at Flemington.

However the mare hasn't won since the Group Two Stocks Stakes (1600m) at Moonee Valley in September last year.

Ortensia, who had the 2010 Group One Galaxy (1100m) at Randwick taken off her due to a positive swab caused by contaminated feed, bounced back to winning form on Oaks Day at Flemington at her first start for Messara.

Ridden by Darren Beadman, the six-year-old finished strongly to beat Balmont by two lengths in the Listed G H Mumm Stakes (1100m).

It was the mare's first win since the 2009 Winterbottom.

"She was impressive during Cup week at Flemington and she has to be a good chance in the Winterbottom again," Williams said.

Williams has also picked up the rides on the Trevor Andrews-trained King Saul in the Group Two Western Australian Guineas (1600m) and the Thompson-trained Saint Encosta in the Listed Tattersall's Cup (2100m).