The Augustan, who won this tournament in 2010, has a two-shot lead, but it could have been more.
The Alabama golfer made bogeys on two of his final three holes (Nos. 16 and 17) and shot 2-over 38 on the back nine after 4-under 32 on the front.
Knox is at 7-under 209 for 54 holes.
Matt Russell, of Dunwoody, is in second place after 69. Michael Garretson, of Acworth, is three back after shooting 75.
Former Greenbrier golfer Chris Waters, now of Athens, is tied for sixth place. He shot 73 and is at 213.
Augusta’s William Sigg had 75 and is tied for 11th place at 218.
Austin Vick, of Evans, is tied for 31st place at 223 after shooting 74.
And Grovetown’s Jamie Felder is tied for 48th place at 226 after shooting 75.