Northern Ireland's Rory McIlroy will take a four-shot lead into the final round of the Masters as he continues his quest to win a first major title.
McIlroy, 21, carded a two-under-par 70 to move to 12 under, four clear of 2009 Masters champion Angel Cabrera, Charl Schwartzel, KJ Choi and Jason Day.
England's Luke Donald (69) is on seven under with Australia's Adam Scott (67).
Tiger Woods (74) finished five under, while defending champion Phil Mickelson (71) moved to three under.
England's Ross Fisher (71), left-handed American Bubba Watson (67), 51-year-old Fred Couples (72), the 1992 champion and Australian 2006 US Open champion Geoff Ogilvy (73) are also at five under.
McIlroy, who will be 22 next month, would become the second youngest Masters champion after Woods won at 21 years, three months and 14 days when he captured the first of his four Green Jackets and first of 14 major titles in 1997.
"It's a great position to be in," said McIlroy."I stayed patient. I'm really happy with the way I stuck to my gameplan and it paid off in the end. I feel comfortable with my game, with the way I've prepared and all of a sudden I finally feel comfortable on this golf course."
McIlroy edged to 11 under with a birdie on the short fourth but handed it back immediately at the tough par-four fifth as playing partner Day took over the lead with a birdie. Day dropped two quick shots to slip back but when McIlroy bogeyed the 10th he found himself in a three-way lead with Day and Choi.
The South Korean quickly dropped two shots though and Day bogeyed the long 13th as McIlroy made a birdie to re-establish a two-shot lead.
Both birdied the par-five 15th, and when Day bogeyed the par-three 16th McIlroy had a three-shot lead over the Australian and clubhouse leaders Cabrera and Schwartzel. McIlroy advanced to 12 under with a 33ft putt on 17 and parred the 18th to put him in sight of a first major title on only his third visit to Augusta. The average for a Masters winner is six trips to Augusta before a first win.
Masters debutant Day, 23, a winner on the PGA Tour last year, is bidding for his first major title and the chance to become the first Australian to win at Augusta, after Greg Norman finished second three times (1986, 1987, 1996).
Choi, 40, placed third in 2004 and fourth last year and is also bidding for his first major, while Cabrera beat Kenny Perry in a play-off for his second major title two years ago.
"Obviously I'm playing my 12th Masters, I've won here before, it's very special," said the 41-year-old Cabrera.
"You've got to see how it evolves, how everybody is playing, how the weather is, and depending on that, then you start making decisions on what kind of strategy you're going to use."
World number four Donald, who was third in 2005, said: "It's put me in a good position, I've still got a great chance, which is always the goal at Majors to be in contention and have a chance."
Woods struggled to get going and missed a golden chance to make up ground when he found the 15th in two. But a three-putt par kept him at six under and a scrappy finish, saving par well on 17 and bogeying 18, dropped him back into the pack.
"I'm pleased with the way I played. I just made nothing," said Woods. "I also had a couple of three-putts out there so not very good. I'm going to have to put together a good front nine and see what happens."
Scottish debutant Martin Laird ended in a group on four under after a second 69, while England's Lee Westwood, last year's runner-up, carded a two-over 74 to slip to three under, with countryman Ian Poulter (71) two under and Justin Rose (also 71) one under.
"I really don't think I can give you my thoughts," Westwood told reporters afterwards. "I'd turn into Wayne Rooney if I attempted to do that."
Spain's Sergio Garcia enjoyed something of a resurgence from his recent slump and climbed to six under with three birdies on the front nine but he bogeyed the 10th and 12th either side of a double bogey on 11, while two more dropped shots on the 14th and 18th saw him finish on one under.
"Well, a disappointing day," he said. "I tried hard, but I don't know, just my head kind of went out on nine and I just couldn't recover. But it's been the same all week. It's a work in progress and we need to get better at it.
"There's been some good positive things and unfortunately today it's been a really bad nine and there's nothing you can do about that."