(CNN) -- Northern's Ireland's Rory McIlroy and Alvaro Quiros of Spain shot seven-under-par 65s to share the lead after the opening round of the Masters at Augusta National Thursday.
McIlroy led for most of the day after his blemish-free morning round until Quiros matched his score with two exquisite late birdies.
They are two shots clear of Korean pair K.J. Choi and 2009 PGA champion Y.E. Yang, who carded 67s.
Matt Kuchar and Ricky Barnes led the home challenge on 68, while defending champion Phil Mickelson fought an errant driver to open with a two-under 70, dropping his only shot of the day at the last.
Four-time Masters champion Tiger Woods finished six shots off the lead after missing a short birdie putt on the last. Bogeys on the tenth and 11th hurt his charge.
The 21-year-old McIlroy also led the 2010 British Open after round one with a blistering 63 but the following day he slumped to an 80 in windy conditions.
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He told reporters he wouldn't be getting carried away. "It was solid more than explosive or spectacular," he said. "I'm not taking anything for granted. It's a good start to the tournament but that's all it is.
"I kept making pars on holes I should birdie and the holes after that I made birdie. It's nice to see a couple of putts drop and it's a great round to build on. I'll take 65 all day long."
As for his experience at St Andrews, when there was a 17 shot difference between his first and second rounds, he said: "I think it'll be a massive help to me.
"Looking back on it, it was a very valuable lesson in my development as a golfer. I'll be thinking about how I can do things better tomorrow than I did there."
England's Ross Fisher, Americans Brandt Snedeker and Gary Woodland, Spain's Sergio Garcia, South African pair Charl Schwartzel and Trevor Immelman, the Masters champion in 2008, and Geoff Ogilvy of Australia were all well-placed after three-under 69s.
But world number one Martin Kaymer, from Germany, had a nightmare start carding a six-over round of 78, while England's Lee Westwood, No.2 in the rankings, ended on level par.