Chris Kirk carded an eight-under 63 on Thursday to earn a one-stroke lead at the end of the opening round of the OHL Classic at Mayakoba.
The American closed with eight birdies and did not drop a single shot on the El Camaleon course, leaving him narrowly ahead of a trio of players tied in second.
Camilo Villegas, Gary Woodland and Ben Crane are all close behind Kirk, who has two top-10 finishes in the new PGA Tour season and won the last of his four Tour titles in 2015.
Woodland was the only one of the top-four contenders to bogey, having come unstuck on the third but recovering soon after with an eagle on the par-five 13th.
Jim Furyk, taking part in his first round of the season, double-bogeyed on the 16th to find himself outside the top 100, while defending champion Graeme McDowell is only slightly better off after opening with a round of 75.
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