Rory McIlroy know he needs a special weekend if he wants to win his first WGC in China. Pictured in Abu Dhabi earlier this year by Fran Caffrey/ McIlroy admits that he has no room manoeuvre now after slipping six shots behind leader Fredrik Jacobson at the halfway stage of the World Golf Championships-HSBC Champions in Shanghai.

The US Open champion shot a rollercoaster second round 69 to finish the day on four under as 37-year old Jacobson hit a flawless 66 to lead by a stroke from Louis Oosthuizen (63) and Adam Scott (65) on 11 under.

On a day when Graeme McDowell left his Valderrama dramas well behind him with a second successive 69 to trail Jacobson by five shots in joint 11th, McIlroy was left to rue a few unforced errors.

“It wasn’t really what I was looking for,” McIlroy said after mixing seven birdies with four bogeys. “I felt as if I could have been a lot lower. I’ll need to do something pretty good over the weekend if I want to try and win this tournament.

“Every time I made a birdie, I made a bogey and I was just always trying to play catch up. I feel like over the past two days, I’ve left quite a few shots out there. But it’s one of those things. I just have to try and make them up over the weekend.”

McDowell had five birdies and two bogeys in his 69 as Jacobson came from two shots behind overnight leader Keegan Bradley to lead.

“I think I’ve just been striking the ball really well,” he said. “I’ve been driving the ball really well over these first two days.

“I got a new driver from Callaway a couple of weeks ago and started with it last week. They are coming out with a new model and it just seems to work really well.

“I’ve been hitting it a little bit further than before - I think last week there was not much run in the fairways and this course is playing pretty long sometimes. 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.”

Bradley is two behind now after a 70 with England’s Paul Casey (66) American Bo Van Pelt (68) tied for fifth and only three behind.

Former world No 1’s Martin Kaymer and Lee Westwood shot 68’s to finish in a four man group on seven under alongside Aaron Baddeley and Thongchai Jaidee.

Michael Hoey shot a 70 to move up to tied 59th on two over but Darren Clarke crashed to a 76 and is tied 68th in the 78-man field on five over.

The 43-year old Ulsterman has been in horrific form since he won the Open at Sandwich in July and broke par in just five of the 19 competitive rounds he has played since lifting the Claret Jug.