SECOND ROUND-12: D Johnson (US) -7: R McIlroy (NI), B Weekley (US), B Watson (US) -6: T Fleetwood (Eng), I Poulter (Eng), E Els (SA), S Garcia (Spa) Selected others: -5: J Rose (Eng), P Mickelson (US) -3: L Donald (Eng), J Donaldson (Wal) -2: P Casey (Eng), G McDowell (NI) SHANGHA I. Long-hitting American Dustin Johnson matched the Sheshan Golf Club course record to surge into a commanding five-stroke lead after the second round of the $8.5 million WGC-HSBC Champions tournament.On a day when first round leader Rory McIlroy’s season-long struggles returned to haunt him on the back nine and pushed the Northern Irishman back into a tie for second with Americans Bubba Watson and Boo Weekley, Johnson was in a class of his own.He plundered six birdies in the first seven holes en route to a nine-under-par 63 on another pleasant day at Sheshan to rocket up the leaderboard 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 is an aggressive player and he vowed to try 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 U.S. PGA Championship when he received a two-stroke penalty for grounding a club in a sandy lie on the 72nd hole that cost him a place in a playoff.

McIlroy, meanwhile, 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 that point on as he battled to an even-par 72.