British world number three Lee Westwood ended a day of high drama and tumultuous swings of fortune by grabbing a one-shot lead in Thursday's opening round of the Masters. 
The straight-hitting Englishman, who has yet to win a major title, fired a five-under-par 67 at a rain-softened Augusta National where tough pin positions posed all sorts of problems for the game's leading players.
Westwood birdied the par-four 17th, then parred the difficult 18th to edge one ahead of South African Louis Oosthuizen, who stormed up the leaderboard with four birdies in the last five holes, and ice-cool Swede Peter Hanson.
Pony-tailed Spaniard Miguel Angel Jimenez, Italy's Francesco Molinari, Britain's Paul Lawrie, Americans Ben Crane, Bubba Watson and Jason Dufner carded 69s while tournament favourite Tiger Woods eked out a level-par 72 after bogeying 17 and 18.
Westwood, who finished second here in 2010 when he also opened with a 67, was delighted with his strong start in the year's first major.
"There was no weakness out there today in my game. I hit it close, hit a lot of fairways and rolled in some nice putts," said the 38-year-old, who has six times finished in the top three at majors.
"When this golf course is soft, it obviously gives you a bit more of a chance, but I think they were slightly worried about the scoring getting out of control, so they tucked a lot of the flags away.
"You can play your way out of a tournament in the first round, and I haven't done that, so I'm right where I want to be and looking forward to the next three days."
Oosthuizen, who romped to a seven-stroke victory in the 2010 British Open, steadily worked his way up the leaderboard after making a slow start before ending his round with a 20-foot birdie putt at the 18th.
Oosthuizen may have tamed the tricky 18th in the opening round but the hole took a brutal toll on many of the players and both Woods and Henrik Stenson came unstuck there. Woods bogeyed the hole after driving well left into the pine trees and Swede Stenson, who had led the field by two shots standing on the 18th tee, wound up with an ugly quadruple-bogey eight.
"I hit some of the worst golf shots I've ever hit today," four-times Masters champion Woods said after offsetting three birdies with three bogeys.
"I squeezed a lot out of that round. I just hung in there and grinded my way around the golf course and stayed very patient, stayed in the moment. I could have shot one, maybe two better, but I got a lot out of that round."
US Open champion Rory McIlroy, who squandered a four-shot lead going into the final round here last year, recovered from a double-bogey at the first to shoot a 71.
British world number one Luke Donald returned a 75, and had to be cleared to keep playing in the Masters after officials investigated a mix-up over his score that turned out to be an administrative error. Three-times Masters winner Phil Mickelson ended a roller-coaster day with a birdie at the last for a 74 that included a triple-bogey seven at the 10th.
Leading first round scores: 67: Lee Westwood (Britain), 68: Louis Oosthuizen (South Africa), Peter Hanson (Sweden); 69: Paul Lawrie (Britain), Miguel Angel Jimenez (Spain), Francesco Molinari (Italy), Ben Crane (US), Jason Dufner (US), Bubba Watson (US); 70: Zach Johnson (US), Jim Furyk (US), Vijay Singh (Fiji), Scott Stallings (US); 71: Ross Fisher (Britain), Stewart Cink (US), Padraig Harrington (Ireland), Steve Stricker (US), Aaron Baddeley (Australia), Hideki Matsuyama (Japan), Matt Kuchar (US), Henrik Stenson (Sweden), Keegan Bradley (US), Nick Watney (US), Patrick Cantlay (US), Kevin Chappell (US), Kevin Na (US), Angel Cabrera (Argentina), Rory McIlroy (Britain); 72: Martin Kaymer (Germany); Bill Haas (US), Justin Rose (Britain), Charl Schwartzel (South Africa), Tiger Woods (US), Ian Poulter (Britain).
