Tiger Woods blamed a lack of preparation time for putting him in a bad spot at the Greenbrier Classic.
Coming off a win last week at Congressional, Woods shot a 1-over-par 71 Thursday and was eight strokes behind first-round leader Vijay Singh on the Old White TPC Course.
He'll need some improvement on Friday to keep pace with a field that amassed 62 under-par rounds Thursday.
Woods committed to the Greenbrier Classic in May and didn't play Old White for the first time until Wednesday. He needed 31 putts in the first round and said the greens were slower than those in his last three tournaments.
"I was a little bit off with my game, and on top of that I didn't have the speed of these greens at all," said Woods, the tour leader this year with three victories. "I missed literally every single putt high today."
The greens were far more forgiving on approach shots than last year, when they were reseeded and Scott Stallings won at 10 under.
Singh had his best round in six months, shooting a 7-under 63 to lead Jeff Maggert, Jonathan Byrd and Martin Flores by one stroke.
"Gosh, I don't know where that came from," the 49-year-old Singh said. "I've been playing pretty good golf for a while, but just never got any scoring going. But today seemed I hit it close and drove the ball really well, hit a lot of greens and made some nice putts."
The last time Singh played this well was an 8-under 64 in the first round of the Farmers Insurance Open at Torrey Pines in January.
Singh is playing in his ninth tournament in 10 weeks with two top-20 finishes in that span. Last week, he also got off to a fast start but shot 81 in the final round and tied for 49th.
Something clicked Thursday, when he made six birdies on the back nine, finishing with four straight.
"Hopefully it keeps going," Singh said. "I don't feel tired. I feel really energized. I've been working really hard on my game, so it's nice to see something happen."
Singh earned the last of his 34 PGA Tour wins four years ago and will be eligible to join the Champions Tour in February.
Maggert, a year younger than Singh, has had to earn his PGA Tour card through qualifying school in two of the last three years. He hasn't won since the 2006 St. Jude Classic and missed the cut in more than half his tournaments this year, including last week.
Although he feels he has a disadvantage off the tee compared with younger players on the 7,274-yard Old White, Maggert used strong iron play to make four birdies on his front nine.
Asked to describe his birdie putts, Maggert joked, "At my age, it's hard to remember — short-term memory's going."
He didn't need a big measuring stick — three of his six birdies overall were from less than 10 feet in a bogey-free round.
"I feel really comfortable here," Maggert said. "There's a lot of guys out here in their 40s, late 40s, that can really play some good golf still. So it's not surprising to see some of the old guys up on the leaderboard."
Byrd has five career wins and already has five top-10 finishes this year. He hadn't played since the U.S. Open and fought through a nagging cough to finish birdie-bogey-birdie Thursday.
Flores had a rare bogey-free round that was his second best of the year. He spent the majority of 2011 on the Nationwide Tour, now called the Web.com Tour.
Playing alongside U.S. Open champ Webb Simpson and Steve Stricker and starting on No. 10, Woods birdied two of his first three holes in his final tuneup before the British Open in two weeks.
On the par-5 17th, he drove into a hazard, took a penalty stroke and three-putted from 20 feet for double bogey.
Phil Mickelson matched Woods with a 71. Mickelson vowed to focus more on golf this time after taking advantage of the resort's numerous amenities with his family last year and missing the cut.
"I didn't play that bad (Thursday)," Mickelson said. "But I made some mistakes there that were just a little sloppy."
Simpson, J.B. Holmes, Andres Romero and Garth Mulroy shot 65. K.J. Choi was among a group of seven at 66.
Stallings birdied his final three holes Thursday for a 67.