Colt Knost shot a 6-under 66 on Friday to take a two-stroke lead over Carl Pettersson after the second round of the RBC Heritage.
Knost, tied for the first-round lead with Chad Campbell and Vaughn Taylor after a 67, had three birdies in a four-hole stretch midway through the round and finished at 9-under 133.
Pettersson had a 65, his best ever showing in 32 career rounds at Harbour Town Golf Links. Two-time RBC Heritage winner Boo Weekley (66) and Harris English (68) were another shot off the lead at 6 under.
World No. 1 Luke Donald rebounded from an opening 75 to shoot 69 and slip inside the 2-over par cut line. Donald needs to finish eighth or better to stay ahead of No. 2 Rory McIlroy.
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