Rory McIlroy lies six shots behind leader Webb Simpson after the opening round of the WGC Bridgestone Invitational at Firestone Country Club.
McIlroy lies in a tie for 19th position on level par following a round which included five birdies, three bogeys and a double bogey at Akron.
Graeme McDowell is a shot worse off in joint 31st place on one over.
The Portrush player, who was named European Tour Golfer of the Month for July, started with a double bogey.
World number eight McDowell carded two birdies and a bogey in the remainder of his round as he aims to build on his victory at the French Open last month.
Henrik Stenson is second after round one on five under, with Ireland's Shane Lowry two over.
McIlroy, ranked three in the world, is struggling for form, having recently missed the cut at the Open Championship at Muirfield.
The Northern Ireland player finished fifth at Akron last year and went on to win the US PGA Championship at Kiawah Island a week later.