World number two Rory McIlroy carded an opening 70 to trail the leaders by five shots at the Wells Fargo Championship at Quail Hollow in North Carolina.
The 22-year-old, who can overhaul the absent Luke Donald at the top of the rankings with a top-seven finish, had four birdies in a two-under-par total.
World number three Lee Westwood and Tiger Woods both returned rounds of 71.
Americans Ryan Moore, Stewart Cink and Webb Simpson all reached seven under and are one shot ahead of the field.
McIlroy, who is 23 on Friday, won the tournament in 2010 but missed the cut last year.
The Northern Irishman, who faded to a share of 40th at the Masters at Augusta in April, three-putted the final green for his second bogey of the round.
"I feel the conditions were pretty perfect, there wasn't much wind and the greens were receptive so 70 probably wasn't good enough," he said.
"I strugggled with the driver, didn't hit many fairways and if you do that round here you'll struggle to score."
Former Masters champion Phil Mickelson drove out of bounds on the fourth hole and racked up a triple bogey but recovered to an opening round of 71.
Meanwhile reigning Masters champion Bubba Watson, who won the famous green jacket after a play-off with Louis Oosthuizen, has decided to take a month away from the sport to spend with his wife Angie and their recently adopted two-month-old son Caleb.
One of the events Watson will miss is next week's prestigious Players' Championship at Sawgrass.
"The Players is one of the best weeks of the year but bonding with my son and wife is what it is all about right now," he said. "Sorry to disappoint fans but the Players has one of the best fields all year, tourney is more than fine without me."