Rory McIlroy endured a tricky start to the Wells Fargo Championship at Quail Hollow Club in Charlotte where Phil Mickelson shot a seven-under par 64 to seize a two-stroke lead on the opening round.
McIlroy, seeking an eighth top-10 finish in 10 appearances in North Carolina, had an uneven round of one-over 72 to sit tied for 73rd.
Shane Lowry and Seamus Power are both a shot better off on level par after respective rounds of 71.
Mickelson, who turns 51 next month, notched eight birdies against only one bogey to surge to the top of the leaderboard. He ranks ninth all-time with 44 wins on the PGA Tour, one behind Walter Hagen (45) for eighth place, but does not have a top-20 finish this year or since turning 50 last June.
Starting on the back nine, Mickelson was even through four holes before a sizzling stretch of five birdies in a six-hole span paved the way for him becoming the oldest player to leader/co-lead after any round in tournament history.
"The biggest thing for me was I was able to say in the present and focus on each shot," Mickelson said after shooting the lowest score by any player 50 or older in the event's history. "My mind has been prone to wander."
Kyoung-Hoon Lee of South Korea and Keegan Bradley are tied for second place after carding matching scores of five-under-par 66.
Six more players are three strokes behind Mickelson at four-under. That group includes Peter Malnati, Luke List, Gary Woodland, Keith Mitchell, Kyle Stanley and Tommy Fleetwood.
McIlroy wasn't the only leading player to find turbulence on the opening round. US Open champion Bryson DeChambeau needed birdies on two of his final three holes to come away with a one-under-par 70, Patrick Cantlay and Xander Schauffele each finished alongside McIlroy at one-over.
