Jack Nicklaus declared himself "disappointed" after beginning his final Open Championship with a three-over-par 75 at St Andrews.
Nicklaus reached the turn level, but three bogeys in a row from the 11th damaged his hopes of making the cut.
"I probably got what I deserved," said the 'Golden Bear', who played in a group with fellow former Open champion Tom Watson and England's Luke Donald.
Watson also had three bogeys on his back nine to match his old rival's 75.
Both players began their rounds with birdies at the first before dropping shots at the second.
Nicklaus, 65, then found the long grass at the 480-yard par four fourth and picked up his second bogey of the day.
But there was a huge cheer when he birdied the seventh after a beautifully judged approach which ran all the way across the green to within five feet of the hole.
Both Nicklaus and Watson began to toil after the turn, with the Golden Bear dropping another shot at the 11th and both players bogeying the 12th and 13th.
Another bogey followed for Watson - five times an Open champion - at the 17th.
"I started off nicely with a birdie, three-putted the second and then didn't play very well for a while," said Nicklaus, who won two of his 18 major titles at St Andrews.
"I saved myself with some nice par putts and when I birdied the seventh I thought I was going to do something, but I just kept three-putting.
"I finished with some nice shots but I'm disappointed in all to shoot a 75.
"I'm going to have to shoot at least four under because I don't think par will be good enough to make the cut."
Another golfing legend, Tony Jacklin, was rolling back the years with some aplomb until he came to the par-five 14th at one over.
The 61-year-old, who wanted to play at the Open one more time with his friend and rival Nicklaus, got himself into deep trouble and came away with a triple bogey eight.
A double bogey followed on the 15th and a final bogey on the 17th saw the 1969 champion slip to a disappointing seven over.