AUGUSTA - Jordan Spieth, bidding to become the youngest ever Masters winner at 20, and 2012 champion Bubba Watson will take a share of the lead into Sunday's final round at Augusta National. After a gruelling day of jousting atop a packed leaderboard under a hot sun that scorched the already devlish greens, the two Americans emerged tied at five-under par 211.

Spieth had a two-under 70, while 35-year-old Watson, who had led by three overnight, settled for a 74. In second place, a stroke behind, were American Matt Kuchar, who had a 68, and unheralded Swedish newcomer Jonas Blixt with a 71. But with 13 players under par and within four strokes of the lead, the stage was set for yet another Sunday afternoon of action-packed drama under the Georgia pines. Spieth, who last year at age 19 became the youngest winner of a PGA Tour event since 1931, said that it had been the toughest of tests on an unforgiving layout. "We could tell early on that the greens were ridiculous. They were so fast that balls would pass the hole and come back a couple of feet," he said. "But that is just the Masters. You can't let your focus go astray for a moment. (The course) is a great fit for my game and so far so good."

If he wins, Spieth would take the youngest Masters winner tag from Tiger Woods, who was 21 when he won his first major at Augusta National in 1997. He would also be the first rookie to win the Masters since Fuzzy Zoeller in 1979 and just the third ever to do so. Waston, who struggled with his putter all day said he was looking forward to playing with Spieth in Sunday's final pairing. "That's my worst day, but I am still tied for the lead, so it's not too bad," said Watson. "Being in the last group gives you confidence for heing in that position. It will be interesting -- me trying to win, him trying to win. Hopefully one of us will win."

Watson opened with a bogey, but on the back of an eagle at the second, he had a five-stroke lead while teeing off at the third. But four holes later he had been reeled in by Blitz, Spieth and Danish veteran Thomas Bjorn, to be joined shortly after by Kuchar on five under. A superb approach for birdie at the 10th hole, where he clinched his playoff victory over Louis Oosthuizen two years ago, stopped the rot and ahead of him his rivals started to falter.  Both Bjorn and Blixt hit their approaches into Rae's Creek in front of the par-five 13th, Kuchar overcooked his approach from the back of the 18th and Spieth dropped one at the 11th to leave Watson two clear again at six under. Already in the clubhouse on three under were 50-year-old Spanish shotmaker Miguel Angel Jimenez, who had a tournament-best 66, and American favorite Rickie Fowler with a 67.

Watson then had chances to extend his lead, but over-hit his approach to the par-five 15th and needed three to get down from the edge of the green at the par-three 16th. Spieth birdied the 15th and then parred his way in to get to five. Minutes later, Watson had a stroke of luck when his badly pulled approach to the last was bunted back by a packed gallery gathered around the hole and he managed to get up and down from there for par.

British hopes will be with 40-year-old Lee Westwood, who moved up the leaderboard with a 70 to get to two under, tied for seventh with Bjorn (73)and US veteran Jim Furyk (72). Defending champion Adam Scott of Australia found himself going backwards as he stumbled to a 76 and at one over, his chances of becoming the first back-to-back Masters winner since Woods in 2002 looked dim. Earlier in the day, Gary Woodland produced a blistering display of shotmaking to match the Masters record of 30 for the front nine, generally regarded as being the harder of the two nine-hole stretches. But he came undone around Amen Corner, the feared trio of holes from 11 to 13 at Augusta National and had to settle for a 69 to leave him at one under.

First out was former world number one and pre-tournament favorite Rory McIlory, who scraped into the weekend by sinking a nervy five-footer for par at the last on Friday evening. The Irishman, playing with a marker, sped round he course in double-quick time and three birdies in the last four holes gave him something to smile about for what is certain to be another doomed Masters campaign.