After missing the cut at the U.S. Open and taking two weeks off, Cook started this tournament with a bogey. But he has played the last 35 holes without one to reach 11-under 133.
"The first one was ugly and I didn't want to do that again," said Cook, who is 24th on the money list this season despite missing the cut in three of his previous four events. "I've made some key putts when I needed to, some good, solid four- to six-foot par putts at times in a round when you need them."
PGA Tour rookie Jonathan Byrd eagled the par-5 15th hole en route to a 4-under 68 that gave him a share of second place at 135 with Australia's Stuart Appleby and Fiji's Vijay Singh. Appleby matched the best round of the day with a 65 while Singh shot 67.