England's James Morrison was the shock leader after two rounds of the PGA Championship here on Friday but world number one Rory McIlroy was heading home after missing the cut.
Morrison shot a 64 for a two round aggregate of 132, twelve-under par, 21 shots better than McIlroy who imploded with a second round 79 and will lose his top-ranked status if Luke Donald finishes eighth on his own or better this weekend.
Morrison, 27, leads by four from defending champion Donald, who had a second successive 68 and overnight leader David Drysdale who followed up his 66 with a 70. Ireland's Peter Lawrie and Alvaro Quiros of Spain were a further shot back in fourth on seven-under.
World number three Lee Westwood made a birdie on the par-5 last to squeeze into the last two days after finishing on 145, one-over par.
Morrison did not have a bogey on his card, making six birdies before a grandstand finish at the par-5 18th where he rolled in a 30-foot putt for an eagle and the second best 36-hole score in this tournament's history. Paul McGinley was 13-under at the same stage in 2008.
Despite his one tour win Morrison is not used to competing in tournaments of this magnitude and admitted he can see Donald out of his rear view mirror.
"I expect a lot but at the same time you have got the likes of Donald and company behind you," he said.
"If I shoot 80 on Saturday or 65 I will take what I can from it. I desperately, desperately want to keep going forward and that is my problem sometimes - I am too keen. I am going to be trying my hardest to win.
"This is my third year on tour and I have won but this is a different level. But that was one of the best rounds I have played and probably one of the easiest, or it felt easy. I wish golf was like that every day but it isn't."
Morrison was a promising cricketer as a youth and played in the same England age-group sides as current internationals Alastair Cook, Tim Bresnan and Ravi Bopara.
He switched to golf aged 16 and within a year he was a scratch player before accepting a scholarship in the United States ahead of turning professional.
Donald got off to a bad start by dropping a shot at the first but five subsequent birdies and an eagle helped him keep Morrison in his sights.
The world number two said: "It is a great opportunity for him - any aspiring golfer would want to get into this situation and see how they deal with it. This is the biggest event on the European Tour. I am sure he will have some nerves and I will try and chase him down."
"Sixty four is impressive. There are opportunities out there and going off early is going to be a help but to shoot 64 around this course is great going."
Gusting winds did not help the afternoon starters and McIlroy suffered more than most as he missed a second cut in a row after failing to make the weekend at the Players Championship.
McIlroy shipped shots consistently through the second round less than three weeks away from his defence of the US Open at the Olympic Club in San Francisco and will heading straight for the range.
He said: "I will have to go and work really hard to get my game back to the level it was before the Masters. I have been putting the work in it is just being more specific.
"I will go and chat to my team and make sure I am ready for the next few weeks. It is just putting the time in on the range and hitting a lot of balls."
