Arnold Palmer has announced that Friday's second round will be his 146th and final in the Masters at Augusta.

"That will be it," said the 72-year-old four-time winner, whose opening 88 today was only one better than his worst-ever round in the tournament.

"I have been thinking about it for some time now," Palmer said.

"I am like everybody else and hoped I would get something going, but when I four-putted the first today the writing was on the wall.

"I am not going to quit all golf, but I just think it's time here. My golf has been pretty lousy of late.

"It will be emotional tomorrow, but these things happen. I'm not sad about it, just sad about not playing well enough to represent the golf I would like to.

"Some things in life are inevitable and I am facing that now. I will support this tournament to the day I die. I love the Masters. But as far as playing it is over."

Earlier, the 66th US Masters almost started with a disaster when three times champion Sam Snead hit a spectator with the opening ceremonial shot from the first tee.

The 89-year-old Snead pushed his drive 100 yards right into the crowd, hitting the fan in the face and breaking his spectacles in the process.

The shaken spectator was given first aid but tournament officials later described his condition as "fine".