Phil Mickelson swept into a four-stroke lead with three birdies in the first four holes of his second round at the BellSouth Classic in Atlanta today.

Already one abreast after a course record-equalling 63, and four ahead of Ireland's Padraig Harrington, the defending champion holed putts of 14 and 13 feet at the start of the back nine, then drove the green at the 310-yard 13th to pick up another shot.

Mickelson stood 12 under par, with fellow American Charles Warren and Australian Gavin Coles eight under and Ian Poulter still in joint fourth spot at six under following four opening pars.

Jose Maria Olazabal, beaten in a play-off by Mickelson a year ago, birdied four of the first six holes to climb to five under and joint seventh, but David Howell fell back from that mark to three under with a disappointing outward 38.

Howell bogeyed the first and second, birdied the long fourth, but then hit his approach to the ninth in the creek right of the green and had to take a penalty drop.

Harrington and Englishman Luke Donald, both of whom started with 68, were among the later starters.