Rory McIlroy struggled to hide his frustration after failing to capitalise on a flying start to the Players Championship at Sawgrass.
While his Ryder Cup team-mates Lee Westwood, Justin Rose and Sergio Garcia all opened with five-under 67s, McIlroy dropped three shots in his last seven holes to return a disappointing 70.
The 25-year-old started at the 10th and birdied his first two holes before giving one back at the 12th, but he got back on track with birdies at 16 and 18.
McIlroy reached five under when he picked up further shots at the first and second, but bogeys at the third, sixth and eighth undid much of his excellent early work.
"I played really solid for the first 11 holes but let a few shots get away from me at the end," said McIlroy, who was five strokes adrift of early leader Russell Henley.
"Guys are going low so 70 is going to be pretty average by the end of the day but I feel like my game is in good enough shape that I can go out tomorrow and shoot something in the 60s.
"It's a course that has frustrated me in the past but I feel like I learnt how to play it last year. I'm coming in disappointed with a 70 when maybe a couple of years ago I would have been happy."
Westwood, who won his 41st professional title in Malaysia last month, shrugged off the surprise of being in the first group to tee off as he cruised to the turn in 33 and birdied 12 and 16 before rounding off a flawless 67.
"It's probably been about 21 years since I was the first ball in the air at a tournament," said the 41-year-old afterwards.
"Actually I had a little chuckle and thought, this is great. This is like having a handicap again, getting a shot. Being first out is brilliant; it's a great tee time. I love it.
"It's better than being last out. Pace of play is nice, no spike marks. Nice playing partners to play with. Yeah, it was a nice morning to be playing golf.
"I played really well. I got off to a nice start and then got a bit of momentum. I hit it good all day.
"It was a really solid 67. I couldn't have really done any worse.
"There's nothing like winning a tournament to give you confidence, more mentally than anything, that when you get into a position to win, you can finish it off.
"I've won 41 times so I'm obviously good at winning when I get a chance. But it's always nice to reaffirm that whenever possible, and I did everything right in Malaysia."