World Number One Rory McIlroy carded a second successive 65 to leap to the top of the leaderboard in the Deutsche Bank Championship.
After starting on the back nine, the two time Major Champion birdied three of his first six holes at TPC Boston.
An eagle on the 18th was followed by another birdie at the first and, although back to back bogeys followed, McIlroy picked up two more shots at the fourth and fifth to return to 12 under.
That gave him a one shot lead over 2010 Open Championship winner Louis Oosthuizen, who matched McIlroy’s score of 65 with the aid of five birdies and an eagle.
"Now that I'm in the tournament, I just want to play as well as I can and maybe reassess things going into the last day," said McIlroy.
"But I was very happy with the two scores that I've got already and know that I need to go out and play just as good tomorrow to give myself a chance going into Monday.
"I got off to a nice start and sort of just kept the momentum going. Everything seemed to work pretty well out there.
"I felt like I drove the ball a bit better today and hit more fairways, which gave me some more opportunities to make birdies, and I was putting well enough to take a few of those."
Ryan Moore and Tiger Woods shared third on ten under after rounds of 68, with Charl Schwartzel, another man to shoot 65, among those one further back.
Despite eagling the fourth, first round leader Seung-Yul Noh could only muster a level par 71 and was therefore alongside Schwartzel.
Ian Poulter remained four under, with fellow Englishmen Lee Westwood and Luke Donald one shot worse off following respective scores of 71 and 72.
