English-based Irish jockey Oisin Murphy has won nine Group One races in five countries this year.

But he might not be finished yet.

The 23-year-old gets the chance to add Group One success in Australia at Moonee Valley this weekend.

Murphy returns to Australian racing for the first time in four years, making the trip to ride Godolphin's international visitor Benbatl in Saturday's $5 million Group One Cox Plate in a clash with champion Winx.

Before that he'll jump aboard Irish sprinter Spirit Of Valor in Friday night's $1 million Group One Manikato Stakes.

Murphy spent a couple of months as an apprentice on loan to Flemington trainer Danny O'Brien in late 2013 and early 2014, winning 13 races from 89 rides during the stint.

That Melbourne stay included a stakes win in the Listed Bagot Handicap on the Nigel Blackiston-trained Outback Joe, while he returned later in 2014 to ride at the Melbourne Cup day meeting at Flemington.

It has come as no surprise to O'Brien that Murphy has emerged among the top echelon of riders in Europe in the past couple of seasons and the trainer has also booked the jockey for two rides at Moonee Valley.

"He was always going to make it," O'Brien said.

"He was a gun rider and he's a really smart, good kid.

"We've always followed him and were always very confident that he would make the grade. And we're thrilled that he's had the last couple of years that he's had."

Two of Murphy's Group One wins this year have been on the Saeed bin Suroor-trained Benbatl in Dubai and Germany.

Benbatl is considered the biggest danger among champion Winx's seven Cox Plate rivals, with Benbatl at $8.50 while Winx was $1.22 on Thursday.

O'Brien has booked Murphy to ride last-start Edward Manifold Stakes fourth placegetter Thousand Wishes in the Group Two Fillies Classic and Lycurgus who will be first-up in the Group Two Crystal Mile.

"I think Thousand Wishes is in the right race," O'Brien said.

Murphy's other ride during the two-day Cox Plate carnival is on Benbatl's stablemate Prize Money in Saturday's Moonee Valley Cup.