Tiger Woods lamented inconsistent putting after he battled to a one-over-par 71 that left him six strokes off the early lead in Thursday's (local time) first round at the US$6 million Honda Classic in Palm Beach Gardens, Florida.
Irishman Rory McIlroy has the clubhouse lead after a seven-under 63, with 24 golfers still on the course. Five of his seven birdies came on the back nine.
While South African Rory Sabbatini and American William McGirt had few problems on the way to opening 65s, Woods, in just his third tournament of the year, said he had trouble adapting to the slow greens.
"I hit it probably good enough to shoot at least three or four lower than I did," the 14-times major champion told reporters after playing in relatively benign morning conditions at PGA National in Palm Beach Gardens.
"First four holes, I had good looks (at birdie putts) and didn't make any of them. I hit it good starting out, scrappy in the middle and good at the end."
World number one Woods, who is playing the Honda Classic for only the third time as a professional, said he had misread several putts after being "fooled" by the speed and grain of the greens.
He began his round on the back nine and negotiated that without too many problems, a nine-foot birdie putt at the par-five 18th putting him at one under by the turn.
It was not until the par-four second, his 11th hole of the day, that he finally had a blemish on his card.
After a poor drive, he had tree trouble with his second shot, found a bunker with his third and was unable to get up and down from there en route to an ugly six. He then offset two birdies with two bogeys to end the day at one over.
The Honda Classic signals the start of Woods' serious preparation for the April 10-13 Masters, and the greens at PGA National are vastly different to the slick, heavily contoured surfaces at Augusta National.
If Woods needed any putting tips after taking 30 strokes on the greens on Thursday, he needed look no further than at former Masters champion Zach Johnson, his playing partner on the day.
Johnson made a damaging start with a quadruple-bogey on his second hole, where he put two balls into a hazard guarding the green, but then displayed admirable patience and a positive attitude as he recovered to shoot a 67.
"It was easy to put that behind me," said American Johnson, who clinched his 11th PGA Tour victory at the Hyundai Tournament of Champions in Hawaii in January.
Johnson ended his day two strokes behind 2011 champion Sabbatini and McGirt.
"I gave myself some good opportunities and the putter was really good to me today," South African Sabbatini told PGA Tour Radio.
"Anytime you come into this golf course and shoot under par you're walking away a happy camper."
McGirt had a tap-in birdie at the par-five third and what he described as "some good par-saves in the middle that kept the momentum going".
The Honda Classic field is the strongest on the PGA Tour this year, though it is missing two former major winners in Louis Oosthuizen of South Africa and England's Justin Rose due to injury.
Oosthuizen, who clinched the 2010 British Open, pulled out on the eve of the tournament due to a lingering back problem while US Open champion Rose is recovering from tendinitis in his right shoulder.