Chicago - American Patrick Rodgers fired a seven-under 64 to vault to the top of the leaderboard halfway through the PGA Tour's John Deere Classic on Friday.
Rodgers drained five birdies in one seven-hole stretch before finishing with a bogey on his last hole of the day, the par-four ninth.
"It was nice to keep making birdies and keep the gas pedal down," Rodgers said.
"It was tricky this afternoon with some breeze, but I know 13-under is not going to win the golf tournament, so I got to keep that same mindset for the next two rounds."
He finished with eight birdies and the one bogey to reach 13-under 129 at the Deere Run course in Silvis, Illinois, 257 kilometers west of Chicago.
Bryson DeChambeau is two strokes back of Rodgers in second after a six-under 65.
Zach Johnson, the 2012 winner, had a 67 to join fellow American Charles Howell, the co-leader after the first round, at 10 under.
Howell had a 69 as Americans take up 19 of the top 20 spots on the leaderboard.
"We had a little bit of a breeze out there," Howell said.
"I can't believe the temperatures. Usually it's 100 degrees here in Moline in July. It was a great day. We just really didn't get much going until the very end there."
The highlight of Rodgers' round came on No 3 where he holed his chip shot from 50 feet, giving him a birdie and an 11-under score.
Rodgers, who has played this event more than any other on the PGA Tour, has missed the cut in 13 starts this season, but has reached the weekend in his last three starts.
Kevin Tway (63), Chesson Hadley (64), Chad Campbell (68) and J.J. Henry (64) were tied for fifth at nine under, four shots back of Rodgers. Tway had nine birdies in a 10-hole stretch en route to the best round of the day.
Two-time Masters champion Bubba Watson shot a 70 to make the cut at three under, as did 53-year-old Davis Love (68).
Leading scores after Friday's second round of the US PGA John Deere Classic at Silvis, Illinois (par-71, USA unless noted):
129 - Patrick Rodgers 65-64
131 - Bryson DeChambeau 66-65
132 - Zach Johnson 65-67, Charles Howell 63-69
133 - Chesson Hadley 69-64, Chad Campbell 65-68, Kevin Tway 70-63, J.J. Henry 69-64
134 - Kevin Kisner 69-65, Nicholas Lindheim 68-66
135 - Jonathan Byrd 70-65, Charley Hoffman 67-68, Troy Merritt 69-66, Scott Stallings 71-64, Martin Flores 70-65, Rory Sabbatini (RSA) 65-70, Dominic Bozzelli 67-68, Robert Streb 69-66, Robert Garrigus 67-68, Jamie Lovemark 68-67
136 - Trey Mullinax 66-70, Ben Crane 67-69, Kevin Streelman 67-69, Daniel Berger 69-67, Camilo Villegas (COL) 67-69 , Chez Reavie 66-70, Brian Campbell 69-67, Miguel Angel Carballo 68-68