Patrick Rodgers maintained his two-shot cushion after firing a three-under-par 68 in the third round of the John Deere Classic in Illinois.
The 25-year-old American had taken command at the halfway stage of the tournament thanks to a seven-under 64 in the second round at TPC Deere Run.
Rodgers was unable to match his Friday fireworks but he still produced a mature display to remain at the top of the leaderboard throughout the day as he chases a maiden PGA Tour success.
The world No 177 made a steady start with birdies at the second and seventh before dropping a shot at the ninth.
He bounced back from that reverse with back-to-back birdies at the 10th and 11th and added another gain at the 14th before missing a four-yard par putt at the 15th.
Rodgers held his nerve to hole a similar length putt for par on the 16th and he also made a comfortable par on the 17th after a wayward drive to the right.
Another confident par-saving putt on the 18th then left him on 16-under 197 after 54 holes.
Rodgers, a former world amateur No 1, told Sky Sports: “It for sure wasn’t my best stuff, but I’ll definitely take it; maintaining the lead that I had at the start of the day.
“It’s a nice course to have the lead because you can’t really play hold-on golf out here. You have got to stay aggressive and I knew that 13 under wouldn’t be very good at the end of the weekend and 16 under is not going to win tomorrow.
“So I have got to keep the gas pedal down all day tomorrow.”
Daniel Berger and Scott Stallings head the chasing pack on 14 under after excellent rounds of 63 and 64 respectively.
World No 20 Berger reached the turn in 30 thanks to five birdies and he added four more on the way home, with his only bogey coming at the 13th.
Stallings managed to keep a bogey off his card but he made his charge on the back nine where he posted four of his five birdies and an eagle on the 17th after a superb approach shot to seven yards and a confident downhill putt.
Nicholas Lindheim, who also eagled the 17th, is in fourth place on 13 under following a 66, while Bryson DeChambeau (70), JJ Henry (68) and Jamie Lovemark (66) are one shot further back on an American-dominated leaderboard.
Zach Johnson, the 2012 champion, produced a mixed bag as he failed to make any inroads into Rodgers’ lead after starting in joint-third place.
The highlight of his round was a chip in from 59 feet for an eagle at the par-four 14th, but he followed that with a double bogey at the 15th and also had three birdies and two bogeys in his one-under 70.
Johnson is among a group of 10 players on 11 under which also includes world No 440 Rick Lamb who matched Berger’s 63.
English qualifier Sam Horsfield climbed 11 places to sit at seven under after a third round of 67, including an eagle at the par-five second.