Brian Harman, knocking at the door with five top-10 finishes this year, will take a one-stroke lead into the final round of the US PGA Tour’s John Deere Classic.

The American shot a six-under-par 65 in Saturday’s third round to sit on 17-under to lead compatriot Steve Stricker in the $US4.7 million ($A5 million) tournament at the Deere Run course.

Australia’s Steven Bowditch dropped eight places on the leaderboard after shooting a one-under round to be five strokes off the pace at 12-under in a tie for 11th.

Stricker made eight birdies and just one bogey on his way to a seven-under 64.

While Scott Brown flirted with a 59, but settled for one of the best rounds of the year on tour with a 10-under 61 to stand third on 15-under (198).

Second-round leaders Zach Johnson and William McGirt both shot two-under 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.