Rory McIlroy and Tiger Woods both finished six shots off the pace after the first round of the Honda Classic.
The pair could only manage level-par rounds of 70 at PGA National in Palm Beach Gardens, Florida, as Colombia's Camilo Villegas led the way with a 64.
World No 1 and defending champion McIlroy has struggled to find his form so far this year after switching clubs and mixed two birdies with two bogeys, the second coming at the par-five 18th following a poor chip from the edge of the green.
American Woods, who was runner-up last year, battled back from bogeys at the 10th - his opening hole - and 13th with birdies at the third and seventh, while he also salvaged a par on the sixth after playing from a creek.
Villegas, who is without a victory since winning this tournament by five strokes in 2010 and lost his card last year, produced a storming finish to top the leaderboard.
The 31-year-old, playing on a sponsor's exemption, was only one under after 12 holes but birdied the 13th, 15th and 17th before signing off in style with an eagle three at the 18th when he drilled a three-wood to eight feet.
"It's a tough golf course," said Villegas. "And I like tough golf courses."
Villegas is one clear of a quartet of players which includes South African Branden Grace, who also made a mockery of the "Bear Trap" - the course's three famed holes from 15 to 17 - with four successive birdies to close his round.
Canadian Graham DeLaet and American duo Rickie Fowler and Robert Streb also carded 65s.
England's Lee Westwood made a rock-solid start with four birdies in a flawless 66, but his compatriots Paul Casey and Brian Davis are among the back-markers following eight-over 78s.
McIlroy's fellow Northern Irishman Graeme McDowell is three-under, while Englishman Justin Rose is two-under after finishing with three bogeys in his last four holes.
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