Scott, the second-round leader by one, finished 54 holes at 8-under 202.
Kevin Sutherland held a temporary lead Saturday before two late bogeys. He finished with a 67 and is tied for second place with Bart Bryant (67), Charley Hoffman (68) and Ryan Moore (68) at 5-under 205.
Sergio Garcia, winless worldwide since 2005, had a 65 and is part of a group tied for sixth at 206.
"The important thing for me is keep getting some good confidence on my side and just make sure that I keep going forward," said Garcia, who lost a playoff last year at the British Open. "At least now I have a chance of winning tomorrow. It's just a matter of going out there and probably having to play close to today and see what happens."