The 21-year-old from Northern Ireland comes into Saturday with a 10-under 134 total. Another youngster, 23-year-old Jason Day of Australia, is at 136.

Four-time champion Tiger Woods is coming off a 6-under 66, showing signs of snapping the longest losing streak of his career. He started the round three strokes back, tied for third with South Korean K.J. Choi, but stumbled a bit with a bogey at the first hole.

On a sweltering spring day, Sergio Garcia and Brandt Snedeker made the biggest moves early on, pushing their scores to 7 under. The Spaniard birdied three of the first five holes, while Snedeker had an eagle at the par-5 second hole and followed with a birdie at No. 3.

Before they set off several players started to make their moves.

Brandt Snedeker, the American who came close in 2008 when he finished third behind Trevor Immelman, moved to seven under thanks to an eagle at the second followed by a birdie at the next.

Spain's back-to-form Sergio Garcia joined him with birdies at two, three, and five.

Also among the early birdies were Jim Furyk who got to six under by picking up shots at the second and third, level with South Africa's Charl Schwartzel, who did likewise.

Phil Mickelson, meanwhile, breathed new life into his bid for back-to-back Masters wins with a storming start to his third round.

The 40-year-old Californian began the day on two under, eight strokes adrift of McIlroy, but he birdied the second and third to the delight of his army of fans.

A bogey at the tough par three fourth was a blow, but Mickelson could look to last year's third round for inspiration.

It was on Saturday then that Mickelson made his big move going eagle-eagle-birdie from the 13th to demolish a five-stroke lead being enjoyed by England's Lee Westwood.

The following day he won by three strokes for his third Masters victory.

Only three players — Jack Nicklaus (1965, 66), (Tiger Woods (2001, 02) and Nick Faldo (1989, 90) have successfully defended the title in 74 years of tournaments.

On another scorching hot day at Augusta national, 49 survivors were setting out to position themselves for a Sunday run at Masters glory.

Woods signalled a belated return to form by shooting a six-under 66 in Friday's second round, highlighted by a stunning back nine of 31.

That totally changed the picture at Augusta National as Woods went from flirting with the cut to menacing the leaders.

McIlroy once again was paired with Day, who produced a remarkable 64 on Friday, one shy of the course record held jointly by Nick Price and Greg Norman and matching the best-ever second-round score at the Masters.

How this youthful pair stand their ground in the face of a Woods charge was one of several tantalizing potential scenarios for Saturday, the traditional "Moving Day" at Augusta National when so many great scores have been recorded.

But it was not all about Woods and the new generation.

As Westwood, the top ranking player left in the tournament following world No. 1 Martin Kaymer's failure to make the cut said: "It's more that just Tiger trying to win this tournament.

"There are other guys on the leaderboard who can try and intimidate." He would include himself in that category having positioned himself nicely on Friday with a 67 to stand five shots off the pace. An opening bogey though was not the start he was looking for.

Australian former US Open champion Geoff Ogilvy was looking ominous after back-to-back 69s left him tied for fifth with Spanish bomber Alvaro Quiros, while 2009 PGA champion Yang Yong-Eun, a further stroke back, made it two Koreans in with a shout of becoming the first Asian to win the Masters.

Then there was Fred Couples - level five shots off the lead with Yang, Westwood and young Americans Rickie Fowler and Ricky Barnes - who at 51 was aiming to become the oldest golfer in history to win a major.