Seamus Power shot a one-under-par 69 in the first round at the Texas Children's Houston Open to lie four shots adrift of the lead, with Rory McIlroy a further stroke back on level par.
Power, who began on the front nine saw a dropped shot at 14 cancelled out by a birdie at the par-five 16th.
The Waterford man picked up shots at second, third and fifth, but two further bogeys hampered his progress as he closed for a 69.
That is one shot better off than McIlroy, who is in a tie for 57th.
The 35-year-old made two birdies and bogeys, along with 14 pars, in a low-key first round.
A closing birdie allowed McIlroy to finish on a high.
Three-time major winner Padraig Harrington laboured to a 74.
One over at the turn, Harrington struggled coming down the stretch, with a bogey at 15 followed by a double-bogey after finding water off the tee at 16.
Four players - Argentina's Alejandro Tosti, Ryan Gerard and Keith Mitchell and Canada's Taylor Pendrith, sit top of the leaderboard on five under.
