August 27-30
Olympia Fields CC (North), Olympia Fields, Illinois
$9,500,000
Round 1, Round 3, Round 4

Conditions at Olympia Fields did not improve on Friday, Rory McIlroy and Patrick Cantlay made mistakes but those were inevitable on the toughest test on Tour this year. At the end of the day they were the only players under par for the tournament, tied for the lead at 1-under.

''I think the test is what's helped me focus and concentrate because if you lose focus out there for one second… just one lapse in concentration can really cost you around here,'' said McIlroy. ''I think one of the big keys this week is just not making big numbers. If you hit it out of position, get it back in position, make sure that your worse score is bogey and move on. Honestly, bogeys aren't that bad out here.''

Cantlay chipped in for birdie from 50 feet and holed out a 50-yard wedge for eagle but also double-bogeyed a par 3 then emerged from the thick roungh with a 6-iron to birdie the 18th with a 40-foot putt adding up to a 68, matching the best score for the round.

''It's about as stiff of a test as you would want,'' said Cantlay. ''It's very, very difficult, and you have to play from the fairway, and you have to play from below the hole, frankly. The greens have so much slope on them that you really need to be putting uphill. And so if you're in the rough, it gets exponentially harder to do that.''

One shot behind the leaders at 140 lie Dustin Johnson and overnight leader Hideki Matsuyama who was the only player this week to reach 4-unde parr. He dropped four shots in his last ten holes for a 73 while Johnson birdied his last two holes for a 69.

''I don't know if any rain will matter, really,'' Kevin Kisner said after a bogey-bogey finish ruined an otherwise good day and gave him a 70, leaving him three shots behind. ''I think even par wins the golf tournament.''