Augusta - Australia's Marc Leishman and Sergio Garcia of Spain shared the lead at the 77th Masters on Thursday after both shot six-under 66s in the first round at Augusta National.
Leishman had set the early pace, sparked by four birdies in a row from the 13th, but Garcia matched him late in the day with a bogey-free round that matched his best ever at the Masters, where he debuted in 1999.
Dustin Johnson of the United States was a stroke further back at 67 with six players - Rickie Fowler, Fred Couples and Matt Kuchar of the United States, David Lynn of England, 2008 champion Trevor Immelman of South Africa and Gonzalo Fernandez-Castano of Spain - grouped together on 68.
Tournament favorite Tiger Woods was tucked in with a batch of players on two-under 70 while world number two Rory McIlroy shot level par and three-time winner Phil Mickelson had a 71.
China's 14-year-old prodigy Guan Tianlang, who became the youngest player ever in Masters history, came in with a 73 to preserve his chances of playing at the weekend.
Reigning champion Bubba Watson struggled to a three-over 75
By the end of a day of intense action, 45 players in the 93-strong field were at or under par and within six shots of the lead.
Garcia, the former boy wonder of world golf, disparaged Augusta National last year after a poor final round and doubted his own chances of ever winning a major.
He was four under by the turn and showing off some of the superb shot-making that was his trademark before he lost some of his verve and swagger.
Two more birdies down the back nine brought him in nicely for a 66, which equalled his best-ever round at the Masters, set in the final round in 2004.
Queried about his downbeat comments at last year's Masters, Garcia said that they had been made in the frustration of the moment, although he admitted he still had reservations about the famed Georgia layout.
"I mean, it's obviously not my favorite, my most favorite place, but you know, we try to enjoy it as much as we can each time we come here," he said.
"Sometimes it comes out better than others, but today it was one of those good days. And you know, let's enjoy it while it lasts."
Leishman, the 2009 PGA Rookie of the Year, said that he had learned his lesson from his only previous appearance at Augusta in 2010 when he missed the cut after a second round of 79.
"You just put all your mistakes in the memory bank and try and not make them again, try and learn from them. And I hit it in a lot of bad spots my first year," he said.
"I managed to avoid those spots today. Hopefully I can avoid them for the rest of the week."
Woods opened his 19th Masters campaign looking to crown a remarkable return to the top with a long-overdue 15th major title.
The 37-year-old American, who regained the world number one spot last month after a two-and-a-half-year hiatus, got off to a quiet enough start, but was two under by the turn with birdies at six and eight.
Watched by the new love in his life, reigning Winter Olympic downhill champion skier Lindsey Vonn, the 14-time major winner stayed there until the par-five 13th, where he moved to three-under.
A bogey at the bunkerless 14th hole set him back, but he parred his way in from there to tuck himself nicely in behind the leaders.
"I putted well today," he said. "I didn't leave myself the easiest of putts, so I am very satisfied with myself," he said.
Woods' rival for the world top ranking, McIlroy, blew hot and cold as once again he struggled for consistency with his new Nike golfing equipment.
The 23-year-old Ulsterman, looking for his third major title after wins at the 2011 US Open and the 2012 PGA Championship, went out in two under 34, but three bogeys down the back nine pegged him back as he came in with a 72.
Three-time winner Mickelson was out in two-over 38, but improved on the home stretch to edge under par at 71.
"It's kind of what I kind of anticipated on Tuesday. I thought I would come out a little bit passive and tentative and I did. I didn't feel great starting out or confident. I hadn't been in competition for a while," he said.
"But the back nine ... I started to feel good with my swing, started to have confidence in the shots."
Ahead of McIlroy and Mickelson, Chinese schoolboy Guan made history by becoming the youngest player in Masters history and then showed why he is such an exciting prospect by shooting a battling 73, that included a showtime putt for birdie from the edge of the 18th green.
Collated scores on Thursday after the first round of the 77th Masters at par-72 Augusta National Golf Club:
66 - Marc Leishman (AUS), Sergio Garcia (ESP)
67 - Dustin Johnson (USA)
- David Lynn (ENG), Rickie Fowler (USA), Gonzalo Fernandez-Castano
(ESP), Trevor Immelman (RSA), Fred Couples (USA), Matt Kuchar (USA)
69 - Jim Furyk (USA), Zach Johnson (USA), Adam Scott (AUS)
- Kevin Na (USA), David Toms (USA), Tim Clark (RSA), Lee Westwood
(ENG), Brandt Snedeker (USA), Justin Rose (ENG), KJ Choi (KOR), John Huh
(USA), Tiger Woods (USA), Jason Day (AUS)
71 - John Peterson
(USA), Ryan Moore (USA), Ryo Ishikawa (JPN), Charl Schwartzel (RSA),
Luke Donald (ENG), Ernie Els (RSA), Bernhard Langer (GER), Bo Van Pelt
(USA), Angel Cabrera (ARG), Phil Mickelson (USA)
72 - Russell
Henley (USA), Brian Gay (USA), Mike Weir (CAN), Peter Hanson (SWE), John
Senden (AUS), DA Points (USA), Vijay Singh (FIJ), Yang Yong-Eun (KOR),
Martin Kaymer (GER), Fredrik Jacobson (SWE), Rory McIlroy (NIR), Bill
Haas (USA), Jason Dufner (USA)
73 - Sandy Lyle (SCO), Larry Mize
(USA), Richard Sterne (RSA), Webb Simpson (USA), Graeme McDowell (NIR),
Michael Thompson (USA), Thomas Bjorn (DEN), Steve Stricker (USA), Guan
Tianlang (CHN), Keegan Bradley (USA)
74 - Jose Maria Olazabal
(ESP), Nicolas Colsaerts (BEL), John Merrick (USA), Mark O'Meara (USA),
Jamie Donaldson (WAL), Lucas Glover (USA), Francesco Molinari (ITA),
Louis Oosthuizen (RSA)
75 - Stewart Cink (USA), Bubba Watson
(USA), Scott Piercy (USA), George Coetzee (RSA), Matteo Manassero (ITA),
Henrik Stenson (SWE)
76 - Ted Potter (USA), Kevin Streelman
(USA), Robert Garrigus (USA), Carl Pettersson (SWE), Ian Poulter (ENG),
Steven Fox (USA), Ben Curtis (USA), Martin Laird (SCO), Paul Lawrie
(SCO), Hunter Mahan (USA)
77 - Nathan Smith (USA), TJ Vogel (USA)
78 - Padraig Harrington (IRL), Thorbjorn Olesen (DEN), Michael Weaver (USA), Nick Watney (USA), Branden Grace (RSA)
79 - Tom Watson (USA), Thaworn Wiratchant (THA), Craig Stadler (USA), Hiroyuki Fujita (JPN)
80 - Ian Woosnam (WAL), Ben Crenshaw (USA)
83 - Alan Dunbar (NIR)