Watney, 29, a two-time winner on the PGA Tour, shot a six-under 66 in perfect scoring conditions for a 54-hole total of 13-under 203. That’s three shots better than fellow American Dustin Johnson, 26, and Northern Ireland’s Rory McIlory, bidding the youngest major championship winner in nearly 100 years.

McIlory, 21, shot a 68, his lowest round of the week, aiming for his biggest win ever.

“I'll approach it the same way as I've approached the last three days," McIlroy said. "I'm going to go out there and play my game.”

Golf’s old world rulers, namely World No. 1 Tiger Woods and No 2. Phil Mickelson struggled mightily and has a slim to no chance of a PGA Championship victory.

Woods shot an even par 72 in the third round and is 10 shots out of the lead, after closing to only five shots after finishing his second round early Saturday with a 70. Mickelson shot a one over 73 and is 12 shots back.

“I couldn’t make any putts when I stuffed it in there and I couldn’t get any momentum,” said Woods, who will almost assuredly needs a captains pick to make the U.S. Ryder Cup team, and will finish his second straight season without a major win.

Also in the mix were Germany’s Martin Kaymer, Australian Jason Day and China’s Wenchong Liang who shot a course record 64. All are tied for fourth, four shots behind Watney at 207.

Third Round Leaders

Nick Watney, US, -- 69-68-66--203
Dustin Johnson, US, -- 71-68-67-206
Rory McIlory, NI, -- 71-68-67--206
Martin Kaymer,GER, -- 72-68-67--207
Jason Day, Aus, -- 69-72-66--207
Wenchong Liang, Cin, -- 72-71-64--207