American Luke Guthrie remains in the driving seat after two rounds of the BMW Masters in Shanghai.
The 23-year-old, who opened with a 65 at the par 72 Lake Malaren course, increased his three-shot overnight lead to four after carding a one-under 71 to post a halfway total of eight-under 136.
Guthrie, who finished fifth in last week's PGA Tour event in Las Vegas, made the ideal start with an opening birdie to go four in front of US colleague John Daly and maintained that advantage despite playing the next eight holes in level par.
The back nine looked set to be a different story when he bogeyed 10 and 12 and at one stage Simon Dyson pulled to within a shot after the Yorkshireman birdied the 16th to go four-under for the day and six-under overall.
But Dyson, who had chipped in for eagle at the seventh, double bogeyed the last and dropped back into a six-way tie for second alongside Ricardo Gonzalez, Scott Jamieson, Thongchai Jaidee, Paul Casey and Craig Lee.
Guthrie, meanwhile, kicked five shots clear thanks to birdies at 15 and 17 before a bogey at the last meant a halfway lead of four.
Gonzalez shot the low round of the day - a five-under 67 - to leap 20 places to tied second while Jamieson also moved to four-under with a 68. Jaidee, Casey and Lee all fired 70s for the second straight day, Lee holing his second from 188 yards at the tough par four 16th for an unlikely eagle.
Former world number one Rory McIlroy, still seeking his first win in 2013 after five victories last year, had moved to three under with birdies at the third and seventh but lost momentum after that and finished at one-under after a round of level par 72.
He's now in tied 12th alongside Ryder Cup teammates Lee Westwood and Ian Poulter.
Poulter produced a back nine charge with four birdies in six holes from the 10th but was hurt by bogeys at 16 and 18.
Daly, who had been Guthrie's nearest challenger after a bogey-free 68 in round one, carded a 74 to slip to tied ninth. After a low-key first 12 holes he finished birdie-bogey-birdie-double bogey-birdie-bogey to end the day at two-under.
Race To Dubai battle
Meanwhile, Graeme McDowell's hopes of eating into Henrik Stenson's Race To Dubai lead took a blow after a poor finish.
Second-placed McDowell currently lies 425,573 euros (£362,660) behind the Swede, but with a first prize of 850,000 euros (£725,000) on offer here and a total prize fund of almost £20million in the four events of the inaugural Final Series, the battle to become European number one in Dubai in mid-November is far from over.
FedEx Cup winner Stenson dropped down the field to 28th after a second round 74 left him at two-over but, after looking nicely placed, 2010 US Open champion McDowell dropped three shots in his last five holes to card a 74 of his own.
That left McDowell at even par and in a tie for 19th.