World number three Rory McIlroy hit a one-under-par 71 in the first round of the WGC-Cadillac Championship in Florida, leaving him five shots off the lead.
The Northern Irishman, who has changed his putting grip for this tournament, scored five birdies, but he dropped shots on the 13th and 18th holes.
The four-time Major winner suffered another blow on the ninth hole when he hit a double bogey, leaving him tied 16th in the field.
Scott Piercy and Marcus Fraser currently share the lead on six-under 66, with the former hitting eight birdies and two bogeys and his opponent carding seven birdies and a solitary bogey on the eighth hole.
Phil Mickelson sits one shot off the pace after carding a five-under 67, while world number one Jordan Spieth is three shots behind.