An extra race has been added to the Country Championships series as a last-ditch chance for horses to qualify for the $300,000 final at Randwick.

Racing NSW has announced a Wild Card race over 1280m at Muswellbrook on March 29, six days before the final.

The Wild Card carries prize money of $50,000 and is open to horses not previously qualified via the original seven races in the series.

Only horses that have accepted for one of the regional finals and otherwise meet the conditions will be eligible to contest the Wild Card.

The race will give a horse like King Derota, a barrier scratching from the first heat at Bathurst on Sunday, another chance to qualify.