American Bo Van Pelt made a hole-in-one as some of the early starters thrived in glorious sunshine at the Masters on Sunday while Tiger Woods and Rory McIlroy slipped out of contention.
Four-times winner Woods was four over for the tournament after mixing three bogeys with two birdies in the first 13 holes to lie level with Northern Irishman McIlroy, who was three over for the day.
The two players had been much trumpeted as heavy favourites during the tournament's build-up but Woods was on track to produce his worst finish as a professional at Augusta National.
With five holes to play, the 14-times major champion was tied for 39th, a distant 13 strokes off the lead, and well outside his previous worst performance of joint 22nd at the 2004 Masters.
Pacesetting Swede Peter Hanson, nine under overnight, and second-placed Phil Mickelson were preparing for a mid-afternoon teeoff and the likelihood of both going low in the final round.
Van Pelt, who tied for eighth here last year, took advantage of the traditionally tempting last-day pin positions at Augusta by firing a best-of-the-week, eight-under-par 64, one stroke short of the Masters record.
The 36-year-old American aced the par-three 16th on the way to a sizzling back nine of six-under 30 to post a one-under total of 287.
The 76th Masters was poised for another gripping finale with Hanson being chased by eight players within five shots of his lead, three of them previous major winners.
Fan favourite Mickelson, hunting a fourth green jacket, was alone in second after electrifying the fans at Augusta National with a scintillating 66 on Saturday.
South Africa's Louis Oosthuizen, runaway winner of the 2010 British Open, was a further stroke back at seven under with triple major champion Padraig Harrington of Ireland tied for sixth at four under.
Hanson and left-hander Mickelson were scheduled to tee off at 1440 local (1840 GMT) in the final pairing at the year's opening major.
(Reporting by Mark Lamport-Stokes; Editing by Julian Linden)