About half of the field is on the course, and there is a three-way tie for the lead.
D.A. Points, Stewart Cink and Geoff Ogilvy are at 5 under.
Points is through 15 holes and has birdie Nos. 13 and 14 after getting bogeys on Nos. 11 and 12.
Cink birdie Nos. 12 and 13. He sunk a 59-foot putt on No. 2 this morning for an eagle.
Ogilvy started his day with a bogey on No. 1 but he has birdies on Nos. 2, 3, 4, 6, 10 and 12.
Rory Sabbatini and Jason Day are 4 under.
Others of note: Phil Mickelson is 2 under through nine holes of play. Tiger Woods and Darren Clarke tee off at 1:40 this afternoon.
12:42 p.m.: Sabbatini finished with a bogey on 18 to card a round of 66. He said the bunkers gave him trouble on the par 3s. He bogeyed the par-3 7th and 15th. His wife, herding three kids with her, said with a smile that the course is easier to walk than Congresstional, the course near Washington D.C., where the U.S. Open was held.
12:56 p.m.: Rory McIlroy is on the course. He is 2 under through 15 holes. Like Cink earlier, he eagled No. 2. He hit his drive 291 yards, his approach 230 yards and knocked in a six-footer for the eagle.
12:58 p.m.: Four players are in the clubhouse with the lead at 4 under. Sabbatini, Points, Thomas Bjorn and Cink.
1 p.m.: Jason Day is in sole possession of the lead at 6 under. He started on the back nine and now has four holes remaining. He has birdies on Nos. 2, 5, 10, 13, 16 and 18.