Seamus Power heads the Irish challenge on three under after the opening round at the World Wide Technology Championship at Mayakoba.
The Waterford native carded a 68 which leaves him seven shots off the lead held by Matthew Wolff at the El Camaleon course in Mexico.
Graeme McDowell is on one under, while Shane Lowry is a shot further back on level par after a 71.
Wolff's brilliant 61 propelled the American onto 10 under ahead of Friday's second round, two shots clear of Aaron Wise.
The quartet of Billy Horschel, Chris Kirk, Sergio Garcia and Talor Gooch are tied for third on seven under.
Power posted a solid round with just one bogey on the 18th, while he birdied the second as well as three shots in a row on 13, 14 and 15.
In a mixed round, McDowell carded six birdies, two bogeys as well as a costly triple bogey on the fourth hole.
Lowry managed five birdies but the Offaly man matched that with his tally of bogeys including three in succession on the 16th, 17th and 18th.