Tiger Woods, playing for the first time since the British Open, was four shots off the pace in a tie for ninth.
Olin Browne was alone in second at 64 while Mike Grob birdied three of the final four holes to shoot a 65.
Heavy rains early in the week left the greens soft and, with little wind, the Warwick Hills course yielded plenty of low scores.
"It was probably as easy as we've ever seen it here," Woods said.
Singh equaled his low round of the year.
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