He stands at 19-under-par 197 through three rounds and is one ahead of Joe Durant at Walt Disney World Resort.
Durant fired an 8-under-par 64 on Saturday at the Magnolia Course to move into second place at minus-18.
Justin Rose, who fired an opening-round 60 and held the second-round lead, struggled with his driver on Saturday. He only managed an even-par 72, but is well in the hunt for his first PGA Tour win at 17-under-par 199.
Play rotated between the Palm course, where Rose set the course record with his 60 on Thursday, and the Magnolia course. For the final two rounds, play is contested at the Magnolia course.
On Saturday morning, the second round was completed after the start of play on Friday was delayed nearly two hours because of fog. Everyone finished and the third round was completed on schedule.
Matteson wasted little time in breaking into red figures with a birdie at his first hole. He added birdies at the fourth and fifth to move to 15 under par for the championship.
He chipped in for a birdie from off the green at seven, then sank a 7- footer for birdie at the 10th. The birdie at 10 moved Matteson to 17 under par and into a tie for the lead.
Trouble loomed for last year's leading money winner on the Nationwide Tour. After a good par save at the 11th, Matteson missed a 4-footer for a par at the par-3 12th.
Matteson reclaimed the lost stroke quickly with a 7-foot birdie putt at the 13th. He got back to 17 under par, but now trailed Durant by a single stroke as Durant drained a 6-foot birdie putt at the 14th.
Durant did not collect another birdie the rest of the way, but Rose resumed his place atop the leaderboard. The young Englishman bogeyed two of his first five, but a birdie at 10 got him back into the mix.
Rose added a 5-foot birdie putt at the 13th, then holed a 12-footer for birdie at 14 to match Durant in the lead at minus-18.
The par-four 17th hole became an important one as Rose missed the fairway off the tee, then nearly drained his second shot into water. Matteson hit his approach to 30 feet, then Rose chipped seven feet from the cup. Matteson drained his long birdie try and Rose missed his par putt allowing Matteson to tie for the lead and Rose to fall one back.
At the closing hole, Rose once again missed the short grass off the tee, but Matteson split the fairway with his drive. Rose hit a great approach shot to 12 feet, but Matteson topped him when his second stopped 2 feet from the hole.
Rose missed his birdie putt, but Matteson tapped his in for the 54-hole lead.
If Matteson can hold on and visit the winner's circle on Sunday, he will become the first player to win his first two events back-to-back since David Duval in 1997.
Matteson is not the only former winner this month on tour to be in the mix.
Davis Love III, who won two weeks ago in Greensboro, fired an 8-under 64 and is tied for fourth with Charles Howell III, who shot a 65 on Saturday. The pair is tied at minus-16.
Nick Watney (64), Heath Slocum (66) and Woody Austin (67) share sixth place at 15-under-par 201. Jonathan Byrd (65), Mark Calcavecchia (63), Richard S. Johnson (68), Marco Dawson (69) and Jerry Kelly (68) are knotted in ninth place at minus-14.