• First-round leader McIlroy five shots adrift in tie for second
• Johnson makes six birdies in first seven holes
Dustin Johnson matched the Sheshan course record to move into a five-stroke lead after the second round of the $8.5m WGC Champions tournament.
The season-long struggles of the first-round leader, Rory McIlroy, returned to haunt him on the back nine and pushed him back into a tie for second with the Americans Bubba Watson and Boo Weekley.
The American Johnson made six birdies in the first seven holes en route to a nine-under-par 63 on another pleasant day, after ending the first day in a tie for eighth. "I played really well the last two days," said Johnson, who posted a 12-under-par 132 halfway total.
Johnson, an aggressive player, vowed to increase his lead rather than protect it over the final two rounds. He has won seven times on the PGA Tour, but is perhaps best known for blowing a chance to win the 2010 US PGA Championship, when he received a two-stroke penalty for grounding a club in a sandy lie on the 72nd hole, costing him a place in a playoff.
McIlroy had threatened to run away with the tournament when he recorded three successive birdies to charge to 10-under after eight holes. However, his swing deserted him on the back nine. A poor drive at the difficult par-four 11th led to a bogey and it was a struggle from then on as he battled to an even-par 72.
"I just hit a couple of bad shots and then I guess I just let it affect me a little bit and then I started to doubt myself sometimes. I didn't hit a lot of quality shots on the back nine. I missed the last six greens in a row, so a bit of work is needed on the range this afternoon."
Weekley (67) made a sluggish start, hitting the ball poorly by his own admission, but a wayward shot into the water at his fifth hole seemed to light a fire. He sank a 25-footer to save par and promptly reeled off three birdies from his seventh hole.
Weekley, a self-confessed redneck from the Florida Panhandle region, was asked whether he enjoyed the Chinese culture.
"It's fun. Just can't understand them," he said in his thick southern drawl, adding he had no plans for sightseeing trips in China because "I don't need to see nothing".
Watson, who hails from the same area as Weekley, shot a 69 that included a double bogey from the middle of the fairway at the 10th. "I left a lot of putts out there," the 2012 Masters champion said.