Tiger Woods was in pole position heading into the final day of the BMW Championship in Illinois after a course-record third round 62 at the Cog Hill club.
The American had been tied at the top of the leaderboard with Mark Wilson overnight, but his fellow American fell away badly today with a level-par 71 to find himself tied for sixth with Australian John Senden on seven under. Senden had earlier held the clubhouse lead after his excellent round of 66.
Woods' impressive nine-under-par round featured a delightful eagle at the par-five ninth as he finished his round seven shots clear on 16-under-par.
The world number one's round equals the tournament record set by Jim Furyk at Bellerive last year while the previous Cog Hill record had stood at 63. Woods is a four-time winner of the event.
Woods believes momentum played a major part in his excellent round.
"After I got past the first hole I was doing all right," he said. "It was one of those days that kind of built upon itself.
"I've always liked it this course. I played here even as an amateur in the old Western Open.
"I've always felt comfortable playing this golf course. Even though the golf course has changed this year for us, the routing is still the same, and I've always felt comfortable playing this golf course for some reason, and even though, for instance, they changed Torrey Pines South, I still feel comfortable on the property. And this is very similar to that."
His closest challenger was compatriot Brandt Snedeker and Australian Marc Leishman who were nine-under after rounds of 66 and 68 respectively.
Padraig Harrington continued his steady form in Illinois, adding a 69 to his previous two rounds of 68. That saw the Irishman head into tomorrow's final round sharing fourth with Matt Kuchar on eight under.
European Ryder Cup pair Luke Donald and Sergio Garcia were tied for eighth with Jim Furyk on six-under.