Prolific trainer Danny O’Brien has decided to run Vigor in the Group 1 Mackinnon Stakes at Flemington this Saturday.

Despite not wanting to race the five-year-old this close to the illustrious Melbourne Cup next Tuesday, O’Brien has been left with no other choice to gain the O’Reilly gelding an assured start in the famous Flemington feature.

The decision was made after Racing Victoria’s chief handicapper Greg Carpenter stated that Vigor must run in and win the Mackinnon to guarantee a Cup berth.

Caulfield Cup third placegetter Vigor is currently 28^th in order of elimination, following the scratching of Speed Gifted, for the $5.6million race and without a win in the Mackinnon he risks not making the 24 horse field.

The winner of the Mackinnon Stakes is exempt from ballot for the Melbourne Cup, as is the Group 3 Lexus Stakes victor, also run on Derby Day. With many in-form Melbourne Cup hopefuls set to contest both races, it would be too big a risk not to run Vigor on Saturday in the weight-for-age event where he is allocated to carry 59kg.

Vigor is currently third-favourite for the Mackinnon at $7.50 behind the Chris Waller-trained Rangirangdoo ($3.40) and Zipping ($7).

The Luca Cumani-trained runner Cima De Triomphe threatens to place Vigor’s Cup prospects at risk. The five-year-old grey is also set to contest the Mackinnon and is currently a $17 chance on Saturday. If the international galloper finishes in the top three and Vigor fails to win, Cima De Triomphe will jump to as high as sixth, from his current 38^th, in the Cup elimination order.