Rory McIlroy took control of the USPGA Championship as the final major of the year made up for lost time at Kiawah Island.

Among 26 players unable to complete their third rounds because of Saturday's thunderstorm, the 23-year-old Ulsterman - up at 5.30am to prepare for his remaining 27 holes - went three clear of the field with a five under par 67.

McIlroy achieved that in spite of missing putts of three and five feet when he resumed on the back nine at 7.45am. Last year's US Open champion failed to birdie the long 11th and bogeyed the next, but came back superbly with a 10-foot putt on the 444-yard 15th and then a two-putt birdie at the long 16th.

Two closing pars - the short 17th after he managed to get up and down from sand - kept him at seven under par. "Could have been better," he said before heading off for some rest before a final round starting at 1.45pm. "I gave myself plenty of chances and the start was not what I wanted, but to play the last four in two under was nice."

Swede Carl Pettersson was in second place following a 72, while joint third one shot further back were Australian Adam Scott, South African Trevor Immelman and American Bo Van Pelt, who had the luxury of a lie-in after finishing his 67 on Saturday.

As for Tiger Woods, he was in a tie for sixth five strokes behind after an eventful morning that even included a fight with a cactus plant. Woods' first shot of the day was an eight-footer for par on the eighth and by lipping out he registered his fourth bogey in five holes and fell all the way to joint 17th.

Out in 40 - eight more than McIlroy - his comeback began with a seven-foot birdie putt on the long 11th and he picked up more shots at the 13th and 16th. There was drama and pain for him at the 15th, however, when he tangled with the thorns of a prickly pear cactus after carving his drive.

Woods was limping badly until calling for a towel from caddie Joe LaCava and extracting what he could from his trouser leg and shoes. Vijay Singh led by one after his birdie at the 11th, but the 49-year-old Fijian's bid to become the oldest major winner in history faltered badly with four dropped shots in the next four holes.

He and playing partner Woods, who had shared the halfway lead with Pettersson, birdied the 16th, but neither could get up and down from the sand at the 223-yard 17th and pars on the last meant rounds of 74 for them both.

Ian Poulter had the same score to drop from fourth to tied 10th on one under, while Graeme McDowell was bitterly disappointed to be on the same mark after a closing double bogey gave him a 71.