American Bo Van Pelt charged into a three-shot lead at the Wachovia Championship in Charlotte, North Carolina before rain curtailed second-round play midway through the afternoon.
Van Pelt birdied the first two holes on the way to a record-equalling eight-under-par 64, ending a damp morning at Quail Hollow Club on a tournament best aggregate of 10-under 134.
The 30-year-old from Indiana, chasing his first title on the PGA Tour, mixed nine birdies with a solitary bogey at the par-four fourth to finish three strokes ahead of 2003 US Open champion Jim Furyk.
One of four leaders overnight after opening with a 68, Furyk returned a 69 after bogeying two of his last three holes.
Play was suspended for 90 minutes in the afternoon because of thunderstorms and eventually called off for the day following a half-hour resumption with 74 players yet to complete their rounds.
Davis Love III was alone in third place at six under after carding a second successive 69 while holder Vijay Singh was a stroke further back after a 68 that featured five birdies in his last eight holes.
South African Rory Sabbatini, among the four pacesetters at the start of the day, slipped back to three under after bogeys on 16 and at the last gave him a 73.
Of the other big names, Ernie Els was at two under after shooting a 71 and Spaniard Sergio Garcia at one under after a 69.
Garcia, who was edged out by Fijian Singh in a three-way playoff for last year's title, had been in danger of not qualifying for the weekend after opening with a 74.
The halfway cut was projected to fall at two-over 146 so Ireland's Graeme McDowell should miss it after finishing on seven over.
