Cox Plate favourite Princess Coup will leave New Zealand on Wednesday bound for Melbourne after pleasing trainer Mark Walker with a solid gallop at Tauranga racecourse.

Princess Coup, who is at $3.50 with TAB Sportsbet for Saturday's Cox Plate (2040m) at Moonee Valley, galloped over 1200m on Saturday and cut out the last 600 in around 36 seconds with race rider Opie Bosson aboard.

"She had a nice hitout and we are very pleased with her," Walker told NZPA.

The Cox Plate looms as a contest between females - Princess Coup versus Sydney filly Samantha Miss, with Weekend Hussler to go for a spell after his failure in the Caulfield Cup on Saturday.

Outside of that, the race appears to lack the depth of previous Cox Plates Walker said, though it would still be a tough task to win.

"They don't give them away, races like that."

Princess Coup won her second Kelt Capital Stakes at Hastings in commanding fashion two weeks ago to push her into favouritism for Australasia's richest weight-for-age race.

Her performance in the race will determine whether she continues on and runs in the Mackinnon Stakes (2000m) at Flemington on November 1, a race in which she was an unlucky second to Sirmione last year.

Meanwhile, Bosson's recent troubles worsened yesterday. He was suspended for three weeks after being found guilty of careless riding in the Lion Red Plate at Tauranga. He was also fined $3000.

Bosson faces a judicial hearing over allegations he provided a urine sample for fellow jockey Bruce Herd during random drug testing at a Waikato race meeting earlier this month.

A date for hearing the charges against Bosson and Herd is expected to be set this week.

Bosson is allowed to ride Princess Coup in the Cox Plate, but will miss the Mackinnon Stakes if she runs in that race.

He will also miss Cup week in Christchurch, with his suspension ending after Two Thousand Guineas day on November 15.

Walker's stable has already engaged top Melbourne hoop Craig Newitt to ride on the second and third days of the Christchurch carnival.