MacRae grabbed an extra time winner against rivals Kingussie in last year's final in Inverness, ending a 25 year wait for the trophy.
His vital strikes have also secured Newtonmore their last two championships.
However, the powerful international forward has been struggling with a persistent knee problem and now faces a scan on the troubled joint. He will play no part today against Beauly at the Eilan and may face a period on the sidelines at a crucial time of the season.
Norman MacArthur, the Newtonmore manager, said: "Danny saw a specialist about his knee problem and a scan is being arranged. It seems the best case scenario now is that he requires a cartilage operation."
Kingussie also have problems today with Lee Bain missing after being red carded last weekend.
Kings have not won the trophy since 2006 and have made the sport's blue ribbon trophy their aim this term.