Lee Westwood shot a 5-under-par 67 to grab sole possession of the lead after Thursday's first round of the Masters at Augusta, Ga.
Westwood, still seeking his first major victory, reeled off four consecutive birdies from Nos. 5-8 to match his career-best round at Augusta National in taking a one-shot lead over Louis Oosthuizen and Peter Hanson.
Tiger Woods was five shots off the pace after a bogey-bogey finish in his round of 72 while Phil Mickelson battled a wayward driver and stumbled to a 74.
World No. 2 Rory McIlroy, who led after three rounds last year before collapsing on Sunday, birdied his final two holes for a 71.
Americans Bubba Watson, Jason Dufner and Ben Crane were tied with Paul Lawrie, Miguel Angel Jimenez and Francesco Molinari at 3-under 69.
Jim Furyk, Zach Johnson, Vijay Singh and Scott Stallings were another stroke back at 70. Henrik Stenson had a pair of eagles and was at 5-under with one hole to play but quadruple-bogeyed the 18th to fall back to 71.
Westwood, who has six top-three finishes in his last 14 majors, was a model of precision in hitting 16 of 18 greens in regulation.
“Ball striking was very good," said Westwood, ranked third in the world. "It has been all year.”
Woods, coming off a victory at Bay Hill two weeks ago that ended a 2 1/2-year drought on the PGA Tour, struggled with his retooled swing and had three birdies and three bogeys.
“I hit some of the worst golf shots I’ve ever hit today,” Woods said. "I could have shot one, maybe two better, but I got a lot out of that round."
Oosthuizen, the 2010 British Open champion, birdied four of the final five holes to grab the early lead before Westwood overtook him.
McIlroy couldn't gain any momentum going until the two closing birdies put him among 15 players bunched at 1-under.
“It was huge. I didn’t feel like I had my best out there today,” McIlroy said.
Defending champion Charl Schwartzel was in a group at even-par 72 that included Fred Couples, Mike Weir and Sergio Garcia.
Mickelson hit only eight of 18 greens in regulation and had a triple-bogey at the par-4 10 before rallying with two birdies on the final four holes, including a 25-foot putt on No. 18.