Rory McIlroy revived his chances at the PGA Championship by sinking a 36-foot par putt, rallying to shoot a one-over par 71 in Thursday's opening round at Oak Hill.

The four-time major champion from Northern Ireland, chasing his first major victory since 2014, reached only two of 14 fairways but escaped dense rough with timely shotmaking to grind out a decent score.

"Just not at my best. I'm just struggling with my swing," he said.

"I can definitely hit it better than that."

"I started to see a couple of better golf shots coming down the last few holes. There was a couple of glimmers of hope in there coming in."

Back-nine starter McIlroy opened with five pars but found bunkers at the par-3 15th and par-4 17th and couldn't get up and down either time. Finding a fairway bunker led to another bogey at 18.

World No. 3 McIlroy appeared set to drop another stroke when he went over the green at the second on his third shot, but he rolled a putt up a slope and into the hole from 36 feet to salvage par and turn his round around.

"It was massive. I was just hoping to get done in two and make a bogey," McIlroy said.

Then he hit his tee shot at the par-3 third inches from the hole to set up his first birdie.