- Fredrik Jacobson leads at halfway in WGC event in Shanghai
- The Swede's round of six-under 66 gives him a one-shot lead
- Louis Oosthuizen and Adam Scott tied in second on 10-under-par
- Rory McIlroy five-under in his bid to top the European Tour money list
Sweden's Fredrik Jacobson carded a second round 66 Friday to head the field at the halfway stage of the WGC HSBC Champions event in Shanghai.
Jacobson, a three-time winner on the PGA Tour, is 11-under-par through the opening two rounds and has a one-shot lead over 2010 British Open winner Louis Oosthuizen and world number eight Adam Scott at the Sheshan International Golf Club.
But U.S. Open champion Rory McIlroy, watched by his girlfriend and tennis World No.1 Caroline Wozniacki, trailed by six shots after an erratic three-under-par 69.
McIllroy, who is chasing Luke Donald in the European Tour money list, mixed seven birdies with four bogeys.
World No.1 Donald, who is missing the final World Golf Championship event with his wife expecting their second child, is bidding to become the first player to top the European and PGA Tour money lists.
Pacesetter Jacobson finished his bogey-free round with a flourish, holing a 20-foot birdie putt at the 18th to cement his lead.
"I think I've just been striking the ball really well," Jacobson told the European Tour's official website. "I've been driving the ball really well over these first two days.
"I feel I've been having pretty good distance off the tees, and if I can hit it straight, which I have so far, I'm going to get some good looks with my irons.
"It's been a great couple of days."
Overnight leader and PGA Championship winner Keegan Bradley is fourth on nine-under after a second-round 70, marred by poor putting, one stroke ahead of fellow American Bo Van Pelt.
Tied with Van Pelt is Englishman Paul Casey, with Martin Kaymer and Lee Westwood, who have both been World No.1 this year, Australian Aaron Baddeley and Thongchai Jaidee of Thailand on seven-under.
American Hunter Mahan is in a six-way tie for 11th alongside 2010 U.S. Open winner Graeme McDowell, English trio Justin Rose, Simon Dyson and Ian Poulter and South Korean K.J. Choi.