Defending champion Rory McIlroy rarely struggles at Quail Hollow, with two wins and five total top-10 finishes at the Wells Fargo Championship since 2010, but he stumbled out of the gate on Thursday with a 4-over 40 on his first nine.

McIlroy, grouped with Rickie Fowler and Hideki Matsuyama, started on the back nine and a three-putt double bogey on the 18th dropped the defending champ to 4-over, making him look out of sorts. On a course where scoring has not been a problem for McIlroy, nothing seemed to come easy for Rory on Thursday in Charlotte.

His struggles wouldn't last long as he fired a 3-under 33 on his second nine to post a 1-over 73. The par 5s were important in shooting that 33, as he was able to reach both par 5s in 2 shots, leaving himself two-putt birdies on a day when he was struggling to find the cup with one putt -- on his 10 greens hit in regulation, he had only two one-putts.

Steve Wheatcroft and Andrew Loupe lead at seven-under-par.

Phil Mickelson is tied for ninth at 3-under par.