5. 1966 Billy Casper vs. Arnold Palmer
278-278 (Casper won playoff, 69-73)

With nine holes to go, Arnold Palmer was thinking about records, not the 7-shot lead he had over Billy Casper. "In retrospect," says Palmer, "it was the biggest mental error of my career." Had Palmer come home in 1-over-par 36, he would have broken Ben Hogan's U.S. Open scoring record of 276. However, bogies at 10, 13, 15, 16 and 17 shaved Palmer's lead to one — and erased any chance he had of beating Hogan's mark. The train wreck subsided with matching pars at the 18th, but the steady, hot-putting Casper dethroned the King in a playoff the next day.