Webb Simpson shot a 1-under 69 on Saturday and is tied for third heading into the final round of the McGladrey Classic.
Simpson and world No. 1 Luke Donald are vying for the PGA Tour money title and both have said they will play next week at Disney. Simpson trails Donald by $68,971, but could move into the top spot with a strong round Sunday.
Simpson also is looking for a tour-leading third win this year, which could make him the favorite for PGA Tour player of the year.
Michael Thompson had three early birdies and finished with a 67 to move into the lead at Sea Island, one shot better than second-round leader Billy Horschel. Thompson had one of three bogey-free rounds on the day and is 13-under 197.
Trevor Immelman, who has only two top-10 finishes on Tour since winning the 2008 Masters, matched the Seaside Course record with a 62 and is tied with Simpson at 11 under. Louis Oosthuizen (69), the 2010 British Open champion, Jeff Overton (66), Kris Blanks (66) and Nick O'Hern (69) are tied at 9 under.
Horschel (70) led by as many as three shots and had a one-shot margin when he hit his tee shot at the par-4 16th hole into a lateral hazard. He eventually posted a double-bogey.
Thompson made all three of his birdies on the front nine and parred every hole on the back. He had an 8-foot putt for birdie on the closing hole, but the ball caught a piece of the cup and trickled out.
''I thought it was the best putt I hit all day,'' Thompson said. ''Something yanked it left. But I'm very happy. I played bogey-free on Saturday, which is always a good thing no matter where I stand.''
Horschel, a second-year pro, has competed against Thompson before. Horschel was a three-time All-American at the University of Florida, and Thompson went to Alabama.
Horschel was 14 under through 15 holes on the sunny, windless day. But he got ''too quick'' on his tee shot at No. 16, and watched in dismay as the ball started left and stayed left, dropping into the hazard. He had an 11-foot putt for bogey, and missed it after playing his previous 20 holes at 7-under par, with no bogeys.
''I guess the ball wanted to go in there,'' Horschel said of his shot at No. 16. ''It was a quick swing ... I get a little quick at the top. I'm fortunate to be as close to Michael as I am. I could be two or three shots behind.''
Horschel got up and down for par at No. 18 after his second shot went into a sandy area right of the green. He splashed the ball out and made a 10-foot putt.
''I was rooting for him,'' Thompson said. ''I never root for someone to hit a bad shot.''
Thompson and Horschel continue to thrive on familiar ground. Thompson won the 2008 Southeastern Conference individual championship at nearby Frederica Golf Club, and Horschel won the 2009 SEC title at Sea Island.
''You can't win the tournament on Saturday,'' Horschel said. ''I'm one back and in the final twosome. It would be nice to be one ahead but I'll take it.''
