Rory McIlroy shared the lead with Vijay Singh after reaching the turn in the third round of the PGA Championship on Saturday as overnight joint leader Tiger Woods tumbled down the leaderboard.

A confident McIlroy had five birdies in his opening eight holes for the outright lead but bogeyed the ninth to slip back to six-under for the tournament when a storm warning halted play as dark, threatening clouds approached the Ocean Course.

Woods, who began the day at four-under, bogeyed the fourth, fifth and seventh holes before the delay, undoing much of the good work he did in Friday's classy 71.

Graeme McDowell is in the mix on two under after 11 holes of the third round, while Padraig Harrington just finished ahead of the siren to post one under for the championship, following an excellent three-under 69.

Darren Clarke was one of the early starters and is currently five over for the tournament.

The 14-times major winner, Woods missed a four-foot putt for birdie on the third but then paid the price more for loose shots from the tee.

The former world number one, searching for his first major win since 2008, was five strokes behind McIlroy and Singh after seven holes when a siren sounded to call players off the course.

Another of the trio of overnight leaders, Singh, PGA winner in 1998 and 2004, started off in perfect fashion with a 14-foot birdie putt on the first and a 20-foot putt on the seventh that put him at six-under and level with McIlroy.

Australia's Adam Scott, who narrowly lost the British Open to Ernie Els last month, was bogey free and made four birdies to make 32 in his front nine, leaving him just a shot off the pace.

Sweden's Carl Pettersson, the other member of the trio of second round leaders, recovered from his bogey on the third with a birdie on the par-three fifth to remain at four-under.

Three Americans put themselves in the frame for Sunday's final round as Bo Van Pelt, Steve Stricker and Jimmy Walker all carded five-under 67s.

Van Pelt held the clubhouse lead at three-under, while Stricker was a further shot back and Walker was one-under.

South Africa's Trevor Immelman, who has not had a top-10 finish in a major since winning the Masters in 2008, was level with Van Pelt after making three birdies and a bogey from 10 holes.