Zach Johnson, Rory Sabbitini and Brian Harman shot eight-under-par 63's Thursday to share the first round lead at the John Deere Classic.
Johnson and Sabbatini played bogey-free golf, while Harman had nine birdies and one bogey on the par-71 TPC Deere Run.
They led 2004 British Open champion Todd Hamilton, Australian Steven Bowditch and William McGirt, the best afternoon finisher, by a stroke.
Madison's Jerry Kelly shot five-under-par 67 and is tied for 11th place. Steve Stricker is three-under-par and tied for 24th.
Johnson, who won the Deere in 2012 and lost it to Jordan Spieth in a playoff last year, birdied four of his first five holes and was 6 under on his opening nine.
Harman, who bettered his best round of the year by two strokes, was 2 under through six holes when his caddie, Scott Tway, took ill.
Jay Hatch of Davenport, Iowa, a high school basketball coach, volunteered from the gallery, and carried Harman's bag the last 12 holes, which Harman played in 6 under