Zach Johnson increased his overnight lead from one to three points on Saturday after two rounds of the Mitsubishi Electric Classic at TPC Sugarloaf in Duluth, Ga.

The tournament is using the Modified Stableford scoring system to encourage aggressive play. Rather than scoring relative to par, points are awarded per hole -- minus-1 for a bogey, zero for par and two for birdie. Eagles are worth five points while double bogeys are minus-3.

Johnson finished +13 on the day, and combined with his opening round of +15, sits at +28 heading into Sunday's final round.

The two-time major champion on the PGA Tour carded seven birdies and made one bogey on Saturday. He birdied four of the last seven holes and has a three-point lead over South African Retief Goosen (+25) and seven-point lead over four others.

"(I) hit it nice. Really hit my driver nice with the exception of 18 and maybe one other one if I'm not mistaken," said Johnson. "Encouraged, encouraged with the trajectory of my game."

Johnson, who finished tied for eighth at last week's Senior PGA Championship, is optimistic about his game.

"I was volatile last week. I know I had a decent week from a finish standpoint, but I had 10 bogeys and three doubles," said Johnson, who turned 50 in February and won his first title on the senior tour in March. "It was very colorful, if you will. I'm trying to clean that up."

Goosen improved from +12 on Friday to +13 on Saturday. He picked up 12 points on his last 11 holes, which included birdies on two par-threes.

Asked if his round felt like a score of 66, Goosen said, "I don't know what it feels like really. You don't really -- you're just so much more into points and trying to just birdie every hole. It's funny how it works, you're not really thinking about a score, you're just thinking birdie."

Goosen's countryman Rory Sabbatini, David Duval, George McNeill and Ben Crane are all at +21, while Alex Cejka of the Czech Republic is at +20.

Canada's Stephen Ames fired the best round of the tournament on Saturday with a score of +16 and is tied for 10th at +18. He earned five points on his first hole of the day, making an eagle on the par-5 No. 10.

-Field Level Media/Reuters