Playing on a sponsor's exemption, Wilson has carded three consecutive 65s for a total of 15-under 195, giving him a four-stroke cushion over American Bob Estes (66), South African Tim Clark (69) and Pettersson, who shot a 10-under 60.

Wilson, whose only PGA Tour win came at the International four years ago, had been clinging to a two-shot lead over Clark at the 18th tee but doubled his advantage with a birdie while the South African closed with a bogey.

The 40-year-old journeyman has depended on the sponsors' generosity and playing qualifiers to gain entry into tournaments and winning on Sunday would bring not only a winner's purse of $918,000, but exempt status through 2012, along with invitations to next month's PGA Championship and next year's Masters.

"I know exactly what it means," Wilson told reporters of the possibility of winning the title. "Last year didn't turn out so good and I'm a little more appreciative of getting in tournaments and playing and being out there fighting.

"Sometimes you're playing tournament after tournament and things don't go your way, you think, I have next week.

"I don't have next week, I've got to take advantage of the rounds I have." Several players capitalized on the soft conditions to make big moves up the leaderboard but none more dramatic than Pettersson.

Pettersson, who just scraped in under the one-under cut, shot the lowest score since the event was founded in 1904, and very nearly earned a place among one of golf's elite clubs until he watched his 30-foot birdie putt from just off the 18th green skid past the cup, denying him a 59.

"It was just hovering right on the left side, with six inches less pace it probably would have gone in," the Swede said.

"I'm thrilled to shoot 60 but to shoot 59, I don't know how many chances you are going to get in your lifetime."

Meanwhile in Bro, Sweden, heavy rain has saturated the Bro Hof Slott course near Stockholm and delayed the start to Sunday's Scandinavian Masters final round.

KJ Choi of South Korea and Swede Richard Johnson are joint leaders, a stroke ahead of last week's British Open champion Louis Oosthuizen of South Africa.