Rory McIlroy insists he must cut out his “silly mistakes” and go low at Kiawah Island today if he’s to revive his hopes of ending his seven-year major drought in the PGA Championship.

The Holywood star (32) bogeyed his last three holes en route to a second round 72 that leaves him tied 39th, eight strokes behind leaders Phil Mickelson and Louis Oosthuizen of South Africa on three-over par.

“I played well, I just didn't get a lot out of the round, “ said McIlroy, who has made five bogeys and played the par-fives in three-over par, which is nine strokes more than Mickelson and seven more than Oosthuizen.

Following a first round 75, McIlroy fought his way back into contention on level par before three closing bogeys undid his hard work.

“Sort of kept it together, and sort of just let it go there the last three holes,” he admitted. “I haven't played the par-5s well this week. That's been the big thing.

“If I'd have played those better, I'd have been right up there, but making five bogeys on the par-5s is not going to get it done.

“I hit the ball much better. I drove the ball much better, I hit the ball much better.

“So if I can keep doing that, just sort of try to keep the silly mistakes off the card, hopefully get out early when there's not as much wind, and try to post a good one.”

Shane Lowry shot 71 and Pádraig Harrington a 73 to leave them tied for 19th on level par.

Five-time Major champion Mickelson (50) shot 69 and 2011 Open champion Oosthuizen a 68 to lead by one stroke on five-under from two-time PGA winner Brooks Koepka, who shot 71.

Like McIlroy, Koepka also finished poorly, missing a short birdie putt at the 16th as well as dropping shots at the 15th and 17th.

“C-plus,” Koepka said, grading his round after making a 10 footer to save par at the 18th.

“I would have been pretty disappointed with even par. I would have felt like I could have played a lot better. But 1-under in these conditions, it's okay.”

South Africans Branden Grace (71) and Christiaan Beuidenhout (70) are tied for fourth with Masters Champion Hideki Matsuyama (68) on three-under.