Former Open champion Leonard was the only player to break 70 as he made light of bad weather and strong winds to move clear of his rivals on nine under.

Leonard will tee off in the final group on Sunday with fellow American Rich Beem, whose 72 left him on six under.

World number one Tiger Woods dropped back to four under as his third-round charge was marred by a bogey at the final hole for a round of 72.

He will play in the second group with Fred Funk, who had led at the halfway point but slipped back to five under with a 73.

The omens are good for Leonard as the last five players who have led going into the final round of the USPGA have won the Wanamaker Trophy.

And Woods has never won a major when trailing after the third round.

Mark Calcavecchia is on four under, with Chris Riley (-3), Rocco Mediate (-1), Jose Coceres (-1) and Steve Lowery (-1) the only other players below par.

Woods, Calcavecchia, Beem and Funk were hit by dropped shots late in their rounds as Leonard birdied the 15th and 16th to consolidate his advantage.

A disastrous round of 79 saw South Africa's Retief Goosen slip out of contention to one over.

And Open champion Ernie Els ended the day on two over after a round of 75.

Earlier in the day Woods had produced one of the best shots of his life to birdie the 18th hole as the second round finally drew to a close.

The 41 players who had yet to complete their second rounds faced a further two-hour wait as groundskeepers and local firefighters attempted to clear three inches of overnight rain from the course.

Woods played his way out of trouble on the last with an unbelievable three iron from a fairway bunker to within 12 feet, and sank the putt.

He finished the opening 36 holes on four under, two behind a group of five tied for the lead at six under.

"That's probably one of the all-time greatest shots I have ever hit," admitted Woods.

England's Justin Rose picked up one stroke on his closing holes to move into contention on two under but a third round of 76 dropped him back to two over.

Sweden's Pierre Fulke began his third round as the best-placed European on four under but joined Rose and Ireland's Padraig Harrington on two over with a 78.