(Reuters) - Dustin Johnson said his score did not reflect the quality of his play, but it was good enough to lift him to a one-stroke lead over fellow American
U.S. Open champion Johnson, the hottest player in the game after three victories since June, carded a three-under-par 67 in the season-ending event at East Lake.
He saved par from six feet at the final hole to post a seven-under 133 halfway total, while Chappell (68) missed a good birdie chance at the last to end the day on six-under.
Johnson and Chappell separated themselves from the pack, with third-placed Kevin Kisner and Japan's Hideki Matsuyama four strokes from the lead at three-under 137.