SILVIS, July 12, 2014 (AFP) - The American shot a six-under par 65 in Saturday's third round to take a one-stroke lead in the $4.7 million tournament at the Deere Run course.
Harman sits at 17-under par 196 with three-time tournament champion and fellow American Steve Stricker in second on 197.
Harman seeks his first US PGA victory but his winless status is not for lack of effort. In the 24 events he has played this season, his best finish is a share of third at the Northern Trust Open.
Stricker made eight birdies and just one bogey on his way to a seven-under 64.
Scott Brown flirted with a 59, but he settled for one of the best rounds of the year on tour with a 10-under 61 to stand third on 198, two shots adrift.
Second-round leaders Zach Johnson and William McGirt both shot 69s to finish in a four-way tie for fourth on 199 alongside South Africa's Tim Clark and American Jerry Kelly who shot 64 and 65 respectively.
Defending champion Jordan Spieth shot a 67 Saturday and was six shots back on 202.
Scores on Saturday after the third round of the $4.7 million PGA John Deere Classic (par 71, USA unless noted):
196 - Brian Harman 63-68-65
197 - Steve Stricker 68-65-64
198 - Scott Brown 67-70-61
199 - Jerry Kelly 66-68-65, Tim Clark (RSA) 72-63-64, Zach Johnson 63-67-69, William McGirt 64-66-69
200 - Ryan Moore 66-67-67, Jhonattan Vegas (VEN) 69-68-63, Johnson Wagner 66-65-69
201 - Charles Howell 66-68-67, Brad Fritsch (CAN) 70-68-63, Steven Bowditch (AUS) 64-67-70
202 - Chad Campbell 69-71-62, David Toms 65-70-67, Daniel Summerhays 69-68-65, Jordan Spieth 71-64-67
203 - Bo Van Pelt 67-69-67, Bud Cauley 67-67-69
204 - Rory Sabbatini (RSA) 63-70-71, Brian Davis (ENG) 72-68-64, D.H. Lee (KOR) 72-66-66, Troy Merritt 68-70-66, Shawn Stefani 73-67-64, Scott Langley 69-70-65