Matteson, who posted a flawless 10-under 61 to open the tournament, turned in another polished effort on the TPC Deere Run layout mixing four birdies with his only bogey through two rounds for a two-day total of 13-under 129.
"If you told me I was going to get 13-under after two rounds I would have taken it and not even teed it up," Matteson said. "It was tough today.
"When I came out I was a little bit more apprehensive after shooting a low one yesterday and obviously I wanted to put a low one out there today.
"It's just always tough when you shoot a low one to come to the golf course the next day...all in all I felt pretty good with what we did today."
Lurking one shot back are compatriots Brian Harman (65) and Jeff Maggert who charged up the leaderboard with an error-free nine-under 62 that included five birdies over his last nine holes to get to 12-under 130.
Two behind the leader are Briton Gary Christian (66) and Americans J.J. Henry (64), Robert Garrigus (66) and Ricky Barnes (67), who missed a chance to join Maggert with a bogey at his final hole of the day the par four ninth.
Champion Steve Stricker, who is looking to become just the fifth men's player to win the same tournament in four consecutive years, sits one shot further adrift at 10-under after signing for a four-under 67.
"I'm three back right now...but the scores are low, 13-under is leading," said Stricker. "You got to believe it could be somewhere around that 20 (under) mark, so that means I've got to shoot 10 more under on the weekend.
"That's a couple good rounds again, or more...I would like to get a nice couple good rounds in. I'm in a good spot."
Fan favourite John Daly, who had made the cut in five of his six starts this season and was coming off a solid tie for 12th at the Greenbrier Classic, failed to make the weekend missing the four-under cut by two strokes.