The 29-year-old was five under after 10 holes but dropped a shot on the fourth, his 13th, before regaining it on the penultimate hole.
That was enough to give him a one-shot lead over fellow Americans Robert Garrigus and Scott Stallings who were alongside European Ryder Cup star Francesco Molinari.
A run of four consecutive birdies from the first to the fourth helped Stallings to a four under par total while Garrigus also recorded seven birdies and three bogeys on his way round.
Molinari was the most consistent of the bunch, dropping just a single shot on his way round.
American veteran Jim Furyk was a further shot back after firing a 68 and he was alongside Charley Hoffman, Cameron Tringale, Matt Jones and Harold Verner III who were all in the closing stages of their rounds.
Brian Harman was also three under after just three holes but there were some big threats a shot further back with Charl Schwartzel, Lee Westwood and KJ Choi all in the clubhouse at two under.
US open champion Justin Rose, Hunter Mahan and Harris English were all in the group at one under having completed their rounds while Jason Dufner, Webb Simpson and Louis Oosthuizen were on the same score but had only just gone out on course.
Ian Poulter had a disappointing day as he shot a one over par 72 while Darren Clarke, Nicolas Colsaerts and Bubba Watson were amongst the late starters.