McIlroy double bogeyed
14 and bogeyed
the last for a poor 74.
After a birdie and bogey at three and four, he went one under at the 14th but immediately bogeyed
the next, only to make amends on 18.
Scotland's Stephen Gallacher had been in outright second after a birdie on the ninth took him out in 33, but the debutant bogeyed
the 10th, 11th and 12th, before pulling a shot back on 15.
But the Australian held his nerve on the closing holes and picked up a birdie on the par 5 15th, while Kuchar, two playing groups ahead, bogeyed
the 16th then double-bogeyed the last to lose his winning chance.
four of his last seven holes, including a nasty double bogey on the 15th.
Starting on the back nine, the American bogeyed
the 11th before a run of three birdies saw him surge up the leaderboard.
When he also bogeyed
the 17th he and Casper were tied and a seven-shot lead had gone.
Bentham was out in a lacklustre 39 and looked as though he might struggle to stay on the heels of the leaders, having double bogeyed
the par four six, but three birdies in the final four holes helped him to an inward nine 33 for a 72 to add to his 70 of the previous day.
He dropped a shot at the sixth, ran up a triple bogey six at the 238 yard seventh, and bogeyed
World No 1 Westwood was on course to be three under par - currently good enough for a share of fifth place - but bogeyed
the seventh and shot a double-bogey six at the ninth, his last hole, to slip back into a share of 35th instead.
Lyle opened the tournament with a double bogey six, but five successive birdies from the 13th lifted him to three under before he bogeyed
the last for a 70.
Vijay Singh had a chance to join Goosen in the clubhouse on five-under-par but he undid a bogey-free round that left him five-under after 17 holes when he double bogeyed
the 18th to finish with a 67.