“It was okay,” McIlroy said. "I started well, two-under through 12, coming through part of the course where you’re looking to pick a couple of shots up on 13, 14 and 15 and I played that stretch of holes in three-over.

"So if I just could have had that three-hole stretch back, but I think other than that, I played nicely. Did what I needed to do. Birdied the par-fives, birdied the holes that you should birdie."

Believing he will be right in the mix if he can shoot in the 60s today, he added: "I can see a low one out there. It’s just a matter of not shooting yourself in the foot too often like I did today.”

Denmark’s Olesen, 27, holed a 30 footer for birdie at the 18th for 67 at a punishing Quail Hollow before being joined at the top late in the day by 33-year old Kisner.

They lead by a shot from US Open champion Brooks Koepka, Texans Gary Woodland and Chris Stroud, 23-year old Web.com Tour graduate Grayson Murray and 40-year old American DA Points on four-under par.

With Spieth forced to finish birdie-birdie-par for a 72, it was an ultimately disappointing day for McIlroy, who bogeyed the 13th and double bogeyed the driveable 14th before missing three birdie chances inside 20 feet at the 15th, 17th and 18th.

Graeme McDowell posted a battling 73 and Shane Lowry a 74 but Pádraig Harrington made four double bogeys in a 79 as McIlroy frittered away a good start.

The Holywood star opened his account by chipping in for birdie at the third but then bogeyed two par threes in a row, airmailing the 181-yard fourth before flubbing a chip from greenside rough at the sixth.

Despite that, he still looked comfortable and used his driver brilliantly to move back into the red, two-putting the par-five seventh before chipping to three feet at the 349-yard eighth to notch back-to-back birdies.

After getting up and down for another birdie the par-five 10th, he was within two shots of Olesen before finding the firm and fast Quail Hollow greens a handful on the way home.

Forced to hole a slick nine footer for par at the 11th after spinning his 100-yard approach off the green, he made a six footer for another par at the 12th but missed from 10 feet for par at the 13th before running up a disastrous double bogey six at the 344-yard 14th.

The world No 4 tried to drive the green but pulled his three-wood into the lake, then fluffed his pitch after a penalty drop and missed from inside five feet for par.

After missing birdie chances from 10 feet at the 15th and 12 feet at the 17th, he parred the last to finish the day just one ahead of Spieth.

“I'm just disappointed with that three-hole stretch, but I'm right in it," said McIlroy, who complained about the grainy greens was outscored by playing partners Rickie Fowler (69) and John Rahm (70).

The thick Bermudagrass rough caused major problems but McIlroy found the greens tougher late in the day.

"The greens were difficult," he said. "If you just hit a putt a tiny bit off line, it exaggerated it. It was tough to hole putts this afternoon.

"Hopefully, the surfaces are a little better tomorrow morning and we can hopefully hole some more putts.”

Spieth showed his trademark grinding qualities to finish birdie-birdie-par for a one-over par 72 after a rare off-day on the greens.

He went out in level par but slipped to three over par after back to back three putts at the fifth and sixth before birdies at the seventh and eighth helped him salvage a 72.

"It was just the putter," Spieth said. "Everything else was fine."

Irish Open champion Rahm was three under with three to go but bogyed the 16th and 17th as Fowler recovered from a triple bogey seven at the fifth by playing the remaining holes in three-under for his 69.

Lowry was one under par with eight to play, but despite dropping four shots in his last eight holes, he was pleased that the battled well.

“God help anyone who doesn’t drive the ball well out there today, it is just so difficult,” said Lowry said, who was frustrated his group was put on the clock on his 11th hole, causing him to make the first of four back nine bogeys there.

“I feel like I played nicely," Lowry said. "The golf course is so difficult, and the greens are so firm that if you put yourself out of position it is just so hard to make pars.

“What pleased me most was how hard I fought out there.”

Fowler, Tony Finau, Jim Herman, Patrick Reed, Paul Casey and Brian Harman posted two under 69s to share eighth place as world No 2 Hideki Matsuyama shot a one under 70 matched by Korea's Sung Kang, World No 1 Dustin Johnson, England's Tommy Fleetwood, Jason Day, Bud Cauley and Louis Oosthuizen.

McDowell was one under after six holes but bogeyed the 17th, first and third before following a birdie at the sixth with a closing bogey.

"I drove it very straight but I drove it very short all day," said McDowell, who holed little on the greens.

"I couldn't get much pressure on the driver, which was a little frustrating, so I had to play the golf course with a lot of club in my hand, which is obviously difficult.

"But I actually played, really, really, really well. I hit a lot of quality approach shots and gave myself some looks and couldn't seem to take them.

"Obviously, I have only played the US Open but watching and reading between the lines, this is the toughest test of the four majors this year.

"Thankfully it is playing tough because if the boys had been making a ton of birdies, I don't think I really could have competed on this golf course.

"As though as it is, if I can shoot a couple under tomorrow I think I will be there or thereabouts going into the weekend."