Leader Lee Westwood edged closer to securing his first Major title after extending his advantage to three shots in The 142nd Open Championship at Muirfield.
The 40 year old Englishman began the day with a two stroke lead over World Number One Tiger Woods and another American Hunter Mahan, but both his rivals encountered problems.
It was not all plain sailing for Westwood either as trouble off the third tee resulted in a bogey five but a brilliant third shot approach to the 559 yard fifth set up a ten foot birdie to get back to three under.
By that time Woods had bogeyed the first, fourth and sixth to drop to two over.
Mahan went back to one over after two bogeys as the challenge was taken up by Westwood's Ryder Cup team-mate Ian Poulter and four-time Major winner Phil Mickelson.
Poulter began the day eight off the lead but his round sparked into life with an eagle three at the ninth.
He followed that with birdies at the tenth, 11th and 12th and missed by inches a nine foot attempt at the 13th.
Mickelson, who started at two over, dropped a stroke at the par five fifth but birdied the equally-long ninth to get to even par.
That was also the score of Sweden's Henrik Stenson, who opened with two birdies in three holes to get into red figures, only to three-putt the par four eighth for bogey.
Poulter's momentum was halted when he missed the par three 16th green and failed to get up and down.
Stenson drove through the ninth green in two to get down in four for birdie and move back to one under.
Scott's round then sparked into the life with birdies at the seventh and eighth, the latter thanks to a monster 50 foot putt across the green.
Woods, from just six feet, missed the chance to hole his first birdie of the day and remained at two over.
Westwood's lead was cut to one as he found the bunker guarding the front of the seventh and failed to get out at the first attempt but holed a vitally-important 12 foot putt for bogey.
And his lead disappeared at the eighth as his approach was short, finding the bunker, and he left himself a putt from the front for par and could not sink it.
He was joined, along with Stenson, on one under after Scott left an eagle putt fractionally short on the ninth.