Green, a two-time major champion on the PGA Tour, announced at the 2003 Senior PGA Championship that he would leave the tour to undergo treatment for throat cancer.
'I'm still pretty week from the treatments, but I'm going out there to see what happens,' said Green, whose last appearance was at the U.S. Senior Open at Inverness. 'You've got to start back somewhere and Hualalai is a pretty good place to begin.'
Rachels' season was cut short by a freak injury. He injured his right shoulder in a motorcycle accident and that led to his having to undergo rotator cuff surgery on the shoulder.
'I'm looking forward to starting again. I haven't played competitively in almost nine months and I'm looking forward to getting back in the swing of things,' said Rachels, a three-time winner on the Champions Tour. 'I've missed the camaraderie out on the Champions Tour. It will be fun again to be around both the players and caddies again.'
The MasterCard Championship tees off January 23rd at the Hualalai Resort Golf Club.