Zach Johnson edged third-round leader Troy Matteson in a one-hole playoff to win the John Deere Classic on Sunday.  Johnson posted a six-under 65 in the final round to get into the clubhouse at 20-under 264.  He then birdied the playoff hole to beat Matteson, who carded a two-under 69 Sunday.  Scott Piercy finished third at 18-under, while John Senden was fourth at minus-17.  Three-time defending champion Steve Stricker and Luke Guthrie tied for fifth place at 16-under 268.