The threat of lightning cut short Saturday's third round of the PGA Championship but not before Rory McIlroy had electrified the crowds and Tiger Woods slid backwards under a darkening sky.

Northern Irishman McIlroy, who had not contended for a major title since he won his first at last year's US Open, dazzled with a stunning run of five birdies in his first eight holes to briefly lead by two shots at seven under par.

Though he bogeyed the ninth to end the day level at the top with Fijian Vijay Singh, the mop-haired 23-year-old was in a prime position to push on for victory when the play resumes on Sunday.