Publications
Partners
Gusts of up to 40 kph are forecast for later in the day at Whistling Straits when all the leading groups will be out on the challenging par-72 Straits Course that hugs the shores of Lake Michigan.
Former champion Shaun Micheel was the only player among the first nine to finish the tournament who recorded a sub-par score in the year's final major.
Surprise winner of the 2003 PGA Championship at Oak Hill, American Micheel signed off with a one-under-par 71 for a one-over total of 289.
Swede Carl Pettersson and American world number two Phil Mickelson were making the most significant moves out on the course.
Pettersson birdied the first three holes to lie seven under overall, six shots behind Watney who was scheduled to tee off at 13:35 local (18:35 GMT).
Left-hander Mickelson, winner of the 2005 PGA Championship at Baltusrol, was a further stroke back at six under after covering his first 13 holes in five under.
Top-ranked Tiger Woods, a distant 10 shots off the pace overnight in pursuit of his first major victory since the 2008 US Open, was one over for the day after double-bogeying the par-four 10th.
The 14-times major winner launched his round in ominous style with birdies at the first two holes, the second of them set up by a superb five-wood on to the front of the green from the right rough.
However, he bogeyed two of the next four holes as he continued to struggle for accuracy off the tee and was two under for the tournament with eight holes to play.
The PGA Championship was set for a dramatic finish on Sunday with nine players going into the final round within five shots of the lead.
Of those, six are yet to win a major title, making it very likely that a first-timer will triumph at golf's highest level for a third successive tournament.
"There's some really good players that haven't won a major," Watney said after grabbing a three-shot lead in Saturday's third round. "You've got to start somewhere and hopefully tomorrow will be my day.
"I just need to go out there and keep doing what I'm doing."
Long-hitting American Dustin Johnson and Britain's Rory McIlroy shared second place overnight at 10 under with China's Liang Wenchong, Australia's Jason Day and Germany's Martin Kaymer knotted at nine under.
