Jeff Maggert sunk nine birdies in his second round to move within a shot of leader Troy Matteson while Steve Stricker stayed firmly in contention for his fourth straight John Deere Classic title.
Matteson, who went 10 under for his first round, could only manage three under in his second, with four birdies and a bogey at the 15th, but that was could enough to keep him at the head of the field on 13 under overall.
Maggert, meanwhile, came close to emulating Matteson's first-round fireworks as his nine-under 62 put him a shot back of the leader alongside Brian Harman, himself six under for the day.
Behind them was a group of four men - England's Gary Christian as well as Americans Ricky Barnes, Robert Garrigus and JJ Henry - on 11 under, but it was the man at the head of the group on 10 under demanding much of the attention.
Stricker, champion in each of the last three years, recovered from a bogey on his second hole - the 11th - to card a four-under round and stand out in a group of players tied for seventh which also included Tommy Biershenk and Lee Janzen.
Winning again would enable Stricker to fly to The Open next week having equalled the feat achieved by Young Tom Morris at Prestwick in 1968-72 and also by Walter Hagen at the USPGA Championship, Gene Sarazen in the Miami Open and Woods at both Bay Hill and the Buick Invitational.
"Kind of wasn't the start I was looking for," Stricker told the PGA Tour website. "I was hoping to get a birdie before I got a bogey - or no bogeys at all.
"But I hung in there. I was patient and hit some good shots. I made a nice long putt at 13 and birdied 14, so I righted the ship pretty quickly and got her going in the right direction."
As for the thought of a fourth straight win here, Stricker was just happy still to be around for the third round.
"You've got to make the cut to be able to try to win the tournament," Stricker said. "That's always my first goal, believe it or not, in tournaments: make sure you're playing on the weekend."
Matteson, meanwhile, was pleased with the way he handled the pressure of following up a stellar first round.
"It's just always tough when you shoot a low one to come to the golf course the next day," Matteson said. "I got here early. You get a little out of sync because you're anxious to get out there and play and see what you do.
"But, you know, all in all I felt pretty good with what we did today."
Christian added a five-under 66 to his first-round 65 and said afterwards he was delighted with the way he played.
"This would be the nearest thing to approaching the mythical zone," he said. "Almost there. Not quite there."
With 109 players under par, the cut was made at four under.
Despite a six-under second round, England's Brian Davis missed out on three under overall, with Scotland's Russell Knox one over.
Collated second round scores & totals in the USPGA Tour John Deere Classic, The TPC at Deere Run, Silvis, Illinois, United States of America
(USA unless stated, par 71):
129 Troy Matteson 61 68
130 Jeff Maggert 68 62, Brian Harman 65 65
131 Ricky Barnes 64 67, J J Henry 67 64, Robert Garrigus 65 66, Gary Christian (Eng) 65 66
132 Steve Stricker 65 67, Lee Janzen 67 65, Tommy Biershenk 66 66
133 Luke Guthrie 65 68, Ben Crane 66 67, Zach Johnson 68 65, Ted Potter, Jr. 67 66, Chris Di Marco 66 67, John Senden (Aus) 69 64, Y.E. Yang (Kor) 68 65
134 John Merrick 67 67, Martin Flores 67 67, Bobby Gates 66 68, Scott Piercy 65 69, Chris Couch 67 67
135 Rory Sabbatini (Rsa) 67 68, Duffy Waldorf 66 69, Dicky Pride 67 68, Tom Gillis 66 69, Tim Clark (Rsa) 67 68, Stuart Appleby (Aus) 66 69, Alex Cejka (Ger) 67 68, Tommy Gainey 69 66
136 Chris Kirk 68 68, Nick Watney 68 68, Brendon De Jonge 68 68, Charley Hoffman 68 68, Scott Brown 70 66, J.J Killeen 68 68, Mark Anderson 69 67, Billy Hurley III 68 68, Nathan Green (Aus) 67 69, Matthew Every 71 65, Randall Hutchison 68 68, Hunter Haas 67 69, Ryan Moore 67 69
137 Spencer Levin 66 71, Seung-yul Noh (Kor) 68 69, Jeff Overton 69 68, Steve Wheatcroft 67 70, Jamie Lovemark 71 66, Chez Reavie 67 70, Roland Thatcher 69 68, Jimmy Walker 66 71, Jordan Spieth 70 67, Kyle Stanley 68 69, Erik Compton 68 69, Mark Wilson 69 68, Kevin Streelman 68 69, K J Choi (Kor) 65 72, Camilo Villegas (Col) 71 66, Carl Pettersson (Swe) 68 69
138 Bud Cauley 69 69, Chris Riley 68 70, Scott Dunlap 70 68, Vaughn Taylor 72 66, Marco Dawson 70 68, Bill Lunde 66 72, Mathias Gronberg (Swe) 69 69, Matt Bettencourt 68 70, Blake Adams 71 67, Chad Campbell 68 70, Billy Horschel 70 68, Jerry Kelly 69 69, Chris Stroud 68 70, Danny Lee (Nzl) 70 68, Kevin Chappell 70 68, Alexandre Rocha (Bra) 70 68, Jonathan Byrd 72 66, Josh Teater 69 69
------------The following players failed to make the cut---------------------
139 Brian Davis (Eng) 74 65, Kris Blanks 71 68, David Hearn (Can) 74 65, David Duval 69 70, John Peterson 69 70, William McGirt 67 72, James Driscoll 68 71, Heath Slocum 70 69, Charles Howell III 71 68, Kyle Reifers 74 65, Boo Weekley 69 70, Troy Kelly 68 71, Jhonattan Vegas (Ven) 67 72
140 Garth Mulroy (Rsa) 71 69, Will Claxton 75 65, John Daly 71 69, Joe Durant 71 69, Sean O'Hair 73 67, Ken Duke 72 68, Ryuji Imada (Jpn) 72 68, Marc Turnesa 70 70, Shane Bertsch 69 71, Jason Gore 71 69, Jason Bohn 70 70
141 Ryan Palmer 68 73, Steven Bowditch (Aus) 74 67, Derek Lamely 70 71, D.A. Points 68 73, Arjun Atwal (Ind) 71 70, Sang-moon Bae (Kor) 72 69, Patrick Rodgers 67 74, Rocco Mediate 68 73
142 Patrick Sheehan 67 75, Billy Mayfair 72 70, Brian Gay 69 73, Michael Bradley 70 72, Richard H. Lee 73 69, Kevin Kisner 72 70, Nick O'Hern (Aus) 68 74, Daniel Summerhays 73 69, Patrick Reed 69 73
143 Rodney Pampling (Aus) 72 71, Bart Bryant 71 72, Chad Proehl 74 69, Stewart Cink 71 72, Garrett Willis 74 69, Matthew Jones (Aus) 68 75, Kevin Stadler 69 74, Stephen Gangluff 73 70, Shaun Micheel 69 74, Cameron Beckman 72 71, Russell Knox (Sco) 74 69
144 Kent Jones 72 72, Chris W. Black 73 71, Matt Mcquillan (Can) 73 71, Sung Kang (Kor) 71 73, Kyle Thompson 73 71, Woody Austin 72 72, Todd Hamilton 72 72, Mathew Goggin (Aus) 73 71, Tim Petrovic 69 75, Brendon Todd 70 74
145 Daniel Chopra (Swe) 75 70, Colt Knost 70 75, Edward Loar 73 72
146 Jason Kokrak 76 70, John Hurley 72 74, Miguel Angel Carballo (Arg) 72 74, Gavin Coles (Aus) 74 72, Harrison Frazar 73 73, Charlie Beljan 73 73, D.J. Trahan 73 73
147 Richard S Johnson (Swe) 70 77, Scott Stallings 76 71
149 Joey Snyder III 74 75
150 Frank Lickliter II 78 72
151 Zack Miller 77 74
WD: Pat Perez 72, Bryce Molder 74
