Garrigus, who needs a win to get into the Masters next month, opened with back-to-back birdies on the Copperhead course at Innisbrook and stretched his lead to four shots with a nifty flop shot off the pine straw to set up a birdie on the par-5 fifth.
He still had a four-shot lead when he missed a 4-foot par putt on the 12th hole, but his lead was down to a single shot when he missed a 3-foot par putt on the final hole. Kevin Na chipped in for birdie on the 15th and shot a 68.
Garrigus was at 8-under 205.
''I had fun,'' Garrigus said. ''I'm in a good position. If I play a good round tomorrow, if I shoot under par, they're going to have to come get me.''
The final group was put on the clock on the back nine, and Na received a bad time on the 13th tee. Na was so deliberate that the final group at times was two holes behind along the back nine, though they finished in just under four hours.
Garrigus paid the price, too.
He was given a bad time for the first time in his career, shocking because he is among the fastest players on Tour. In this case, he had a tough lie in the rough on the 14th hole and walked up to the green to gauge his options. That led to the bad time, and Garrigus said he didn't bother looking at his next shot as long as he normally would have. It was a long putt that ran some 15 feet by the hole, but he made that for par.
''Best putt of the week,'' he said.
Garrigus and Na will be in the final group again Sunday, with plenty of company right behind them on the leaderboard.
Na was defensive about the pace, and his reputation.
''I know how to play,'' he said. ''I don't know what people have said, but I don't think I should be criticized.''
Asked how much he has improved since his slow play was on display at The Players Championship in 2012, when he couldn't take a swing or sometimes purposely swung over the ball so he could start over, Na said, ''A ton.''
''It's not fair to me,'' he said. ''I already have that stamp on me.''
John Senden matched the low score of the tournament with a 64 in perfect, sunny weather. He moved up 32 spots to third, and goes into the final round only two shots behind. Justin Rose hit a wild tee shot on the 18th and made bogey, though his 69 left the No. 7 player in the world in reasonable shape. He was three behind.
Retief Goosen made the cut on the number, and then played bogey-free for a 64. He was finished with his round some two hours before the final group even teed off. When the day ended, Goosen was four shots behind in a tie for fifth, along with Charley Hoffman (67) and Scott Langley (69).
Luke Donald had a 67, and those two bogeys by Garrigus gave the former world No. 1 some hope.
''I've played here enough times, and seeing the scores over the last couple days, I knew a good round would shoot me up the board,'' said Donald, who won at Innisbrook in 2012. ''So just try to play my own game and post something low-ish to get me back into contention.''
Pat Perez wasn't as fortunate. He opened with a birdie, but then pulled his tee shot into the vegetation left of the third fairway. A penalty drop would have left the ball just in front of a palmetto bush, so he went back to the tee and made double bogey. He made another double bogey on the back nine with a tee shot into the water on No. 12 and fell out of tournament with a 77.
Na is notorious for fidgeting over his tee shots, and even with the Perez penalty on No. 3, the final group fell far behind and stayed that way.
''They took off,'' Garrigus said. ''When Pat is playing bad, he takes four seconds to hit a shot.''
Seven players were separated by four shots –the size of the lead Garrigus had with seven holes remaining in the third round – and only one of them (Rose) already has a tee time booked for Augusta National next month.
Goosen has plenty at stake even if he doesn't go from the cut line to a win. He has three more tournaments after this to make about $104,000 to retain his card from a major medical extension because of his back surgery.
DIVOTS: The 54-hole cut was at 5-over-par, and 76 players advanced to Sunday. Among those who missed was Luke Guthrie, who started the third round at 2-under and shot an 80. Ricky Barnes shot 42 on the back nine for a 77 to miss by one shot. ... Mark Calcavecchia made a tough up-and-down for par on the last hole that at the time was good enough to make the cut on the number. ''Yay. I think,'' said his wife, Brenda, who caddies for him.