Scott Stallings drained three birdies in his final four holes Thursday to rise to the top of the leaderboard after one round at the Memorial Tournament.
Stallings entered the clubhouse with a six-under 66, and holds a one-shot lead over Spencer Levin and Erik Compton, who both carded five-under 67s.
Below those three players, however, the field is extremely bunched up.
Seven players share fourth place at three-under 69, including Rory Sabbatini, Aaron Baddeley and Brandt Snedeker. Behind that group are nine players who shot minus-two, among them Tiger Woods -- a four-time Memorial champion -- and Ernie Els.
Several high-profile players struggled Thursday, including Masters winner Bubba Watson (75) and Phil Mickelson, who withdrew after shooting a seven-over 79. He cited mental fatigue and poor hitting as reasons for the withdrawal.
"I have to look at what's best for me to play in the U.S. Open, and I'm going to take the next few days to kind of rest up," Mickelson said.
For a good portion of Thursday's round, the lead was stuck at minus-three. At one point, more than half a dozen players were tied for first at that score.
But as the afternoon wore into early evening, the logjam began to break.
Levin jumped ahead of the field thanks to an eagle late in his round. He began his round on the back nine, where a double-bogey at 16 dropped him back to minus-one, but he birdied three and five to regain the strokes.
Then, at the par-five seventh, he stuck his second shot on the green and drained the 24-foot putt.
"I hit a good drive and then hit a three-wood right in the middle of the green," Levin said. "Those are two of the best swings I made all day pretty much. And then I was feeling good with the putter, had a relatively straight putt."
Levin birdied the following hole, but settled for a 67 after a bogey at the last. He has never won on the PGA Tour, but came close at the Phoenix Open in February. The 27-year-old carried a six-shot lead into the final round before blowing it and taking third.
"I'd like to be in that situation again. That would be great," Levin said. "That's a long ways from now, but who knows. Two more good rounds, you never know."
Not long after Levin entered the clubhouse, Stallings did him one stroke better.
He had started his round on the front nine, where he stumbled to a bogey at two before rebounding with birdies at four and five. An eagle at seven got him to minus-three around the turn.
Stallings was stuck at that score following a birdie-bogey stretch from the 11th, but used his strong close to take sole possession of first. He drained a six-footer at 15 and a 14-footer at the par-three 16th. Then, at the last, Stallings stuck his approach within two feet and converted the birdie try.
"Been really struggling with my game coming back from injury, and I was healed, I wasn't healed, and kind of the ebbs and flows that go along with that," said Stallings, who won the Greenbrier Classic last year.
Compton used a similar run to get within a shot of Stallings. He was playing in the final group off the first tee and opening his back nine with consecutive birdies, but a bogey at 12 put him at two-under.
However, he ran off three consecutive birdies from the 14th to rise up the leaderboard. Compton, who has twice received a heart transplant, ended the stretch with a five-yard chip shot.
Daniel Summerhays was in Compton's threesome and twice reached five-under, including after a birdie at 15. But he stumbled to a double-bogey at the next hole to drop back into the fourth-place group.
NOTES: Dustin Johnson returned to competition for the first time since the WGC-Cadillac Championship in early March. He had been out with a back injury, and shot a one-under 71 on Thursday...Rory McIlroy recorded a quadruple-bogey at the 12th, his third hole, but rebounded and also finished with a 71...Sang- Moon Bae (79), Tom Gillis (81) and Boo Weekley (82) also withdrew following the first round.