Phil Mickelson held onto his lead at the Constellation Furyk & Friends where Padraig Harrington and Darren Clarke slipped down the pecking order.
Mickelson will head into the final round of the Champions Tour event with a two-stroke lead after carding a 67 to move to 11-under par.
Behind him is a scramble for second, with Miguel Angel Jimenez of Spain, who shot a 65, Steve Flesh and fellow American Matt Gogel also sitting on nine-under par.
2011 Open winner Darren Clarke was unable to back up his opening day 68 in Jacksonville, with three bogeys, plus a double-bogey at the last ensuring the Irishman is on three-under and eight adrift of Mickelson.
Ryder Cup captain Harrington once again found the going tough, a shot worse off than his opening round 74. Five bogeys were carded on his round, along with two birdies and the 50-year-old sits at five-over.
Jim Furyk founded the event to benefit his charity, the Jim & Tabitha Furyk Foundation, and has expanded it from a one-day pro-am to a regular tournament for the first time.
