CHICAGO, September 15, 2013 (AFP) - Only six players finished their final rounds at par-71 Conway Farms, where play was delayed twice before officials halted the round until Monday morning.
There were still 22 players in the field of 70 yet to tee off, including US leader Jim Furyk, who matched the tour record low round with a 59 on Friday and followed with a 69 on Saturday to stand on 13-under par 200 for 54 holes.
Steve Stricker was second on 201 with defending US PGA playoff champion Brandt Snedeker another stroke back, Zach Johnson in fourth on 203 and world number one Tiger Woods in fifth, four adrift of Furyk in an all-American top five.
Furyk has squandered his past five 54-hole leads, including one last month at the PGA Championship, when countryman Jason Dufner passed him over the final holes to win his first major title.
The top 30 players on the playoff points list after the final round will advance to next week's season-ending Tour Championship at Atlanta, with the top five on that list being assured of winning the playoff crown and a $10 million prize should they win the tournament.
Snedeker, ninth on the points list entering the final round, will be the first defending champion to even reach the final event.
"It's fantastic to have a great year and get back to the Tour Championship," Snedeker said Sunday.
"I really want to be in the top five to control my own destiny. Every position you can crawl up makes a difference. That's what makes these playoffs so much fun."
Woods is projected to pass Sweden's Henrik Stenson and top the points list entering the Tour Championship.
Northern Ireland's Rory McIlroy fired his second 68 in a row before play was halted, giving him back-to-back rounds in the 60s for the first time this season in the same US PGA Tour event. He finished 72 holes on seven-over 291.
England's Lee Westwood, who clung to the 30th and last Tour Championship berth when the week began, fired a 74 to finish on 296, dropping him out of the top 30 in points.
American Dustin Johnson fired a 72 to finish on 293 to claim the 30th position but with so much of the field having so many holes remaining, his grasp upon the spot was tenuous at best.