* Third-round action halted due to threat of lightning
* Round to resume on Sunday with 26 players yet to finish (Adds quotes, detail)
KIAWAH ISLAND, South Carolina, Aug 11 (Reuters) - The PGA Championship finally succumbed to the weather gods when Saturday's third round was abandoned for the day with 26 players yet to finish following an earlier suspension due to lightning.
The players were called off the course at 4:50 p.m. (2050 GMT) as thunderous storm clouds closed in on the Ocean Course at Kiawah Island and the decision to halt the action for the day was taken nearly two hours later.
Northern Ireland's Rory McIlroy, after nine holes, and Fijian Vijay Singh, after seven, held a share of the lead at six under with Australia's Adam Scott alone in third, at five under after nine.
Four-times champion Tiger Woods, joint leader overnight with Singh and Swede Carl Pettersson, bogeyed three of his first seven holes to slip five strokes off the pace.
It is the first time the PGA Championship third round has spilled over into Sunday since the 2008 edition at Oakland Hills Country Club where Padraig Harrington triumphed by two shots.
The third round will resume at 7:45 a.m. on Sunday with the final round scheduled to begin at 11:44 a.m. with the players teeing off from the first and 10th holes in groups of three.
The final group was expected to tee off at 1:45 p.m., organisers said.
"We were fortunate (with weather) yesterday and not so lucky today," PGA Championship managing director Kerry Haigh told reporters. "But the forecast for tomorrow is very positive.
"There is a chance of some lingering showers first thing in the morning, but following that, our weather people tell us we can expect a very good day with winds very slightly less than they have been today.
"With that forecast, the plan we have should certainly allow us to finish on schedule tomorrow evening."
Weather forecasts predicted mainly cloudy and breezy conditions on Sunday with a 30 percent chance of a thunderstorm in the morning.
The 2012 PGA Championship is the 15th event to be suspended or delayed by weather on the PGA Tour this year. (Reporting by Mark Lamport-Stokes; Editing by Frank Pingue and John O'Brien)