Cox Plate winner Ocean Park is stifling betting on Saturday's Mackinnon Stakes after being installed a short priced favourite to land his fifth consecutive Group One victory.

The four-year-old opened at $1.55 with TAB fixed odds on Wednesday with Caulfield Cup runner-up Alcopop ($6) and December Draw ($9) the only others under double figure odds.

Only a handful of Cox Plate winners have backed up in the Mackinnon in the past 20 years and only one successfully.

So You Think claimed the double in 2010 while Fields Of Omagh, Dane Ripper and The Phantom Chance were all beaten as Mackinnon favourites after claiming Australasia's weight-for-age championship.

Ocean Park will face just seven rivals in Saturday's 2000m feature including Winchester and Zabeelionaire who are both safely in the Melbourne Cup field.

Import Prairie Star is 28th in the order of Cup entry but a Mackinnon victory will guarantee him a start three days later.

The race has traditionally been an important Melbourne Cup lead-up but with the increasing presence of the international horses its significance has diminished.

The last Cup winner to successfully use it as a springboard was the Bart Cummings-trained Viewed in 2008.

The only other Mackinnon runner still in the Melbourne Cup mix is New Zealander Back In Black.

A last start fourth in the Geelong Cup, Back In Black is 45th in the order of entry and has to win to earn his spot on Tuesday, although he is a $61 chance to do so.

Glass Harmonium has not been paid up for the Melbourne Cup after failing in the race last year but he will be shooting for his own slice of Mackinnon Stakes history on Saturday.

He will be striving to become the first horse to go back-to-back since Belmura Lad in 1980-81.

Glass Harmonium has undergone throat surgery since last year's race but his form this spring has been indifferent.

After resuming with an encouraging fourth to Moment Of Change in the Sir Rupert Clarke Stakes he beat just one runner home in the Toorak Handicap and again in the Cox Plate.

In contrast, Ocean Park is unbeaten this campaign winning the Makfi Challenge first-up in New Zealand before claiming the Underwood and Caulfield Stakes en route to his Cox Plate triumph.