(CNN) -- With arrow straight driving, big hitting Dustin Johnson powered his way clear of the field at the WGC-HSBC Champions in Shanghai Friday while first round leader Rory McIlroy paid the price for wayward play from tee to green on his back nine.
Texan Johnson overpowered the Sheshan International course with a nine-under 63 to go five clear of McIlroy and fellow Americans Bubba Watson and Boo Weekley on 12-under 132 after two rounds.
Johnson's playing partner Graeme McDowell -- still in the hunt on six-under -- could only look on in wonder. "I've probably seen 18 of the best drives I've seen all year in the last two days," he remarked during their round.
"I really drove the ball well," Johnson told the official PGA Tour website. "For me, that's a big key."
He picked up six birdies in his opening seven holes and after completing a front nine of 30 held it together to come home in 33.
McIlroy, hunting his first tournament win of 2013, also made a fast start with three birdies on the front nine to build on his first round 65.
But coming home it all went wrong for the 24-year-old Northern Irishman -- let down by errant tee shots and approach play to give up three shots to par.
Finding the water on the par-five 18th with his approach shot, McIlroy made a disappointing bogey to finish on level par 72.
"I just hit a couple of bad shots, and then I guess I let it affect me a little bit, and then I started to doubt myself sometimes," McIlroy said.
"I didn't hit a lot of quality shots on the back nine."
He was joined in joint second place by Weekley (67) and Watson (69), the 2012 Masters champion a crowd pleaser on his first trip to China.
"Everything about the trip has been beautiful. Malaysia last week (CIMB Classic) and then here. It's perfect," he said.
McDowell, second in the European Tour's Race to Dubai, shot a second straight 69 to share fifth with England's Tommy Fleetwood and Ian Poulter, Spanish pair Sergio Garcia and Gonzalo Fernandez-Castano and South African great Ernie Els.
British Open champion Phil Mickelson was back on five under with U.S. Open winner Justin Rose.
"I'm making a lot of birdies," Mickelson said. "But I've had too many mistakes," he admitted.
Swede Henrik Stenson, who is leading the Race to Dubai, was completely out of sorts and shot a four-over 76 to stand six-over and in 70th out of the 78-man field.