Rory McIlroy shot his second successive 65 to take the clubhouse lead in the Deutsche Bank Championship at TPC Boston on 12 under par.
Starting from the 10th, the USPGA champion birdied three of his first six holes before an eagle at the 18th completed a back nine featuring six threes.
Another followed for birdie at the first and, though he dropped shots at the next two, successive birdies at four and five completed a good day's work for the 23-year-old from Northern Ireland.
With the top players on the leaderboard all having completed their second rounds, McIlroy was two shots clear of Ryan Moore after the American could only follow his opening 64 with a three-under-par 68 today.
Four birdies and an eagle on the back nine were offset by bogeys at 10, 15 and three to check Moore's progress.
Overnight leader Noh Seung-Yul could not build on his opening 62 as he carded a level-par 71 to remain at nine under alongside Jason Dufner, who shot 66, and fellow round one high-flier Chris Kirk.
Tiger Woods started with two birdies followed by a bogey and was one under for the day through five, eight under for the tournament along with fellow Americans Bryce Molder, in the clubhouse after a round of 69, and Jeff Overton.