Jordan Spieth sets 36-hole record at Augusta

Playing with steely cool and pinpoint precision, the 21-year-old Spieth reached the halfway mark on 14-under-par 130 to surpass the 131 posted by Raymond Floyd on his way to winning the 1976 Masters.

"It's pretty cool any time you can set a record here," said Spieth. "It means that I'm putting well and putting from short distances."

The young Texan, with 15 birdies and one bogey in his two rounds, also equalled the lowest 36-hole total for any major championship.

Spieth led by five over compatriot Charley Hoffman, who made five birdies but bogeyed the last for a 68 for nine-under 135 on a hot, humid day amid the Georgia pines.

South African Ernie Els was another four shots back in third place after registering an even-par 72 for 139.

Tiger Woods moved up the leaderboard, the four-time champion shooting a three-under 69 to stand two under par and in a tie for 13th. He had finished the first round tied for 41st with a one-over 73 in his return to competition after a two-month absence.

Spieth, not among the game's longest hitters but gifted in all facets, served notice last year that his game was fit for competing at Augusta National as he finished tied for second.

"What I learned was patience," he said about his 2014 showing. "I'm not going to get ahead of myself, I'm going to stay in the moment."

The young American began the hot, humid day with a three-shot lead after a sizzling opening round of eight-under-par 64.

He followed a flawless front nine that featured three birdies with a matching effort on the homeward half as he equalled the widest 36-hole lead ever at the Masters.

Also on five-under and hoping to make up some ground were England's Justin Rose (through 10 holes) and Paul Casey (seven holes).

Kevin Na rocketed up the leaderboard to reach four under par after an eagle at the par-five 13th. Na began the day at two over par.

Among players at three-under were former champion Angel Cabrera of Argentina (69), former British Open winner Louis Oosthuizen (69) of South Africa and 58-year-old Mark O'Meara (68).

Other possible targets for Spieth are two Woods records.

Woods won his first of four Masters in 1997 with a record total of 18-under-par 270 for a record 12-shot victory margin.

One Woods record at the Masters was safe from Spieth, who would be the second youngest player to wear the green jacket behind Tiger should the Texan go on to win his first major.

Spieth has made a big splash before. As a 19 year old in 2013, he triumphed in a play-off to win the John Deere Classic and become the youngest winner on the US PGA Tour in 82 years.