Rory McIlroy was stunned to find himself only five strokes off the pace halfway through the PGA Championship as bad as his drives have been at Oak Hill.

The four-time major-winner from Northern Ireland closed with a 16-foot birdie putt to fire a one-under-par 69 in Friday's second round to share 10th on level par 140.

But McIlroy has felt ill at times and managed to find the fairway in only seven of 28 opportunities, spraying errant tee shots in all directions, testing his patience.

"I need to be patient with the way I'm hitting it off the tee," he said. "I stayed really patient. I think my patience was rewarded with a couple of good breaks and a couple of birdies coming in."

If McIlroy could find his form over the weekend, it's not impossible he could end a nine-year major drought.

"I think how terribly I've felt over the golf ball over the last two days, the fact that I'm only five back — not saying I could be up there with one of my best performances, but when I holed that putt at the last, I looked at the board and I thought, 'I can't believe I'm five back,'" McIlroy said.

"I guess that's a good thing because I know if I can get it in play off the tee, that's the key to my success over the weekend. If I can get the ball in play off the tee, I'll have a shot."

That will get trickier on Saturday when rain is forecast all day and thick rough becomes even tougher for shotmaking.

"Even the little bit of rain that we had today, the rough definitely got a lot stickier and thicker," McIlroy said. "The ball was coming out slower out of the rough those last few holes."

McIlroy said he might just go for broke when it comes to ball bashing off the tee.