Second round leaderboard-8 L Guthrie (US)-4 R Gonzalez (Arg)-4 S Jamieson-4 T Jaidee (Tha)-4 P CaseySHANGHAI. 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.