Matteson, who led by a single stroke following Friday's Round 2, overcame a pair of bogeys on the back nine to build the advantage, finishing 54 holes at 18-under 195.
That put Matteson three shots ahead of three-time defending champion Steve Stricker, who also shot a 66 Saturday, ending at minus-15.
Stricker is seeking to become only the fifth player in PGA Tour history to win the same tournament four straight years.
Sharing third place at 14-under 199 were Brian Harman (69) and 2009 runner-up Zach Johnson (66).
Knotted in fifth place at minus-13 were J.J. Henry (69), John Senden (67) and Billy Hurley III (64).